Buy Ki67 Antibody for Research and Clinical Operations

Ki67 is one of the most studied nuclear proteins in cell biology. Expressed exclusively during active phases of the cell cycle (late G1, S, G2, and M) and absent from resting G0 cells, Ki67 gives researchers a precise, reliable marker for distinguishing proliferating cells from quiescent ones. Whether you're mapping tumor growth fractions in oncology studies or tracking lymphocyte activity in immunology research, selecting the right Ki67 antibody directly affects the accuracy and reproducibility of your data.

At MyBioSource, we stock a broad catalog of validated Ki67 antibodies spanning multiple clonalities, host species, reactivity profiles, and conjugation options. This page is your guide to navigating our Ki67 antibody offerings, helping you match the right product to your specific application, tissue type, and detection system.

Why Ki67 Is a Gold Standard Proliferation Marker

Ki67 (encoded by the MKI67 gene, UniProt P46013) is a large nuclear protein with a predicted molecular weight of approximately 359 kDa. It exists as two isoforms (~345 kDa and ~395 kDa) and shows a distinctive cell cycle-dependent localization pattern: perinucleolar during G1, distributed throughout the nuclear matrix at G2, and present on chromosomes during mitosis.

This tightly regulated expression profile is precisely why Ki67 has become the gold standard proliferation marker across research disciplines. Its absence in nondividing cells means positive Ki67 staining identifies the actively growing fraction of a cell population, a critical measurement in:

• Cancer biology: Tumor Ki67 index correlates strongly with histological grade. A low Ki67 index is consistently associated with low-grade neoplasms, making it a prognostic marker in breast, lung, cervical, and other cancers.
• Neuroscience: Ki67 is routinely used as a neuronal marker of cell cycling and proliferation in studies of neurogenesis and neuropathology.
• Immunology: Researchers track lymphocyte proliferation during infection and immune activation using Ki67 antibodies in flow cytometry panels.
• Cardiology: Ki67 has been used to study myocyte proliferation following myocardial infarction.

A well-validated Ki67 antibody for research produces consistent, specific nuclear staining with minimal background, an outcome that depends on antibody quality and proper protocol optimization.

Our Ki67 Antibody Catalog: Clonalities, Host Species, and Applications

MyBioSource carries monoclonal and polyclonal Ki67 antibodies to fit diverse experimental setups. Understanding the differences between these formats helps you select the right tool for your specific workflow.

Monoclonal Ki67 Antibodies

Monoclonal antibodies are produced from a single B-cell clone, giving them highly consistent epitope specificity from lot to lot. For Ki67, popular monoclonal clones used across the research community include:

• MIB-1 — One of the most widely cited clones for formalin-fixed paraffin-embedded (FFPE) tissue in immunohistochemistry (IHC). Excellent for clinical pathology applications and tumor Ki67 index scoring.
• SP6 — A recombinant rabbit monoclonal clone validated across IHC (paraffin and frozen), ICC/IF, flow cytometry, and Western blot. Validated for human, mouse, and rat reactivity.
• SolA15 — A rat monoclonal clone with broad cross-species reactivity (human, mouse, rat, canine, nonhuman primate). Well-suited for flow cytometry applications requiring intracellular staining, available in multiple fluorochrome conjugations.
• 20Raj1 — A mouse monoclonal clone used in IHC-P, ICC/IF, and flow cytometry for human and canine samples.

Monoclonal antibodies are the preferred choice when reproducibility across experiments and assay consistency are top priorities, particularly in multi-site studies or clinical research settings.

Polyclonal Ki67 Antibodies

Polyclonal antibodies recognize multiple epitopes on the Ki67 protein, often resulting in stronger signal intensity. This makes them particularly useful in applications where antigen density may be low or tissue conditions reduce epitope accessibility.

A widely referenced polyclonal in the field is ab15580, a rabbit polyclonal raised against a synthetic peptide derived from within residues 1200–1300 of human Ki67, conjugated to KLH. Ab15580 is an affinity-purified IgG isotype and validated for IHC-P and ICC/IF in human and mouse samples. It has been cited in thousands of peer-reviewed publications, and its specificity has been confirmed by knockout cell line validation using MKI67 knockout HAP1 cells.

Polyclonal Ki67 antibodies are available from MyBioSource in unconjugated and conjugated formats, with reactivity across human, mouse, rat, rabbit, and other species.

Recommended Applications for Ki67 Antibodies

Ki67 antibodies are validated across numerous laboratory techniques, from tissue-based histological methods to single-cell flow cytometry panels, providing researchers with flexibility in interrogating cell proliferation. Matching your antibody format, clone, and conjugation to your detection platform is the most direct path to clean, reproducible results.

Immunohistochemistry (IHC-P and IHC-F)

IHC remains the most common application for Ki67 antibodies in research and translational medicine. For formalin-fixed paraffin-embedded (FFPE) tissues, heat-mediated antigen retrieval in sodium citrate buffer (pH 6.0) is the standard protocol before incubation with your Ki67 primary antibody. Tonsil tissue is routinely used as a positive control.

For best results in IHC:

1. Deparaffinize and rehydrate sections through xylene and graded alcohols.
2. Perform heat-mediated antigen retrieval in 10 mM citrate buffer (pH 6.0) for 10–20 minutes.
3. Block endogenous peroxidase and apply appropriate blocking serum.
4. Incubate with Ki67 primary antibody at the manufacturer-recommended concentration (typically 0.1–5 µg/mL for polyclonals) for 15–60 minutes at room temperature or overnight at 4°C.
5. Detect with an appropriate secondary antibody system (HRP-conjugated or fluorescent), then counterstain with hematoxylin.

Immunocytochemistry / Immunofluorescence (ICC/IF)

For intracellular Ki67 staining in cell culture:

1. Fix cells in 100% methanol (5 minutes) or 4% paraformaldehyde (10 minutes).
2. Permeabilize with 0.1% PBS-Triton X-100 for 5 minutes.
3. Block with 1% BSA / 10% normal goat serum / 0.3M glycine in 0.1% PBS-Tween for 1 hour.
4. Incubate overnight at 4°C with Ki67 antibody at ~0.5–1 µg/mL.
5. Follow with an appropriate fluorochrome-conjugated secondary antibody. Counterstain nuclei with DAPI.

Flow Cytometry

Ki67 flow cytometry panels require intracellular staining protocols since Ki67 is a nuclear antigen. An established protocol includes:

1. Fix cells in 70% ethanol (chilled to -20°C), adding dropwise while vortexing.
2. Incubate at -20°C for at least 1 hour.
3. Wash 3× in cell staining buffer.
4. Incubate with fluorochrome-conjugated Ki67 antibody (approximately 5 µL per million cells in 100 µL) for 30 minutes at room temperature in the dark.
5. Wash and resuspend in staining buffer for acquisition.

Directly conjugated Ki67 monoclonal antibodies (clone SolA15 in FITC, PE, APC, eFluor variants, and Alexa Fluor formats) are preferred for flow cytometry, as they reduce nonspecific binding from secondary antibody steps. Select your conjugate based on your instrument's laser/filter configuration and your existing panel.

Western Blot (WB)

Due to Ki67's large molecular weight, WB requires optimization. Key tips:

1. Load 20 µg or more of protein per lane.
2. Use low-percentage gels (6–8%) or Tris-Acetate gels.
3. Increase SDS concentration and voltage in the transfer buffer.
4. Extend transfer time to ensure complete transfer of high-molecular-weight proteins.

Selecting the Right Ki67 Antibody: Key Decision Criteria

Choosing the right Ki67 antibody starts with understanding your own experimental requirements. Use these criteria to narrow your selection:

1. Sample Type

Are you working with FFPE tissue sections, frozen sections, or live/fixed cells? FFPE compatibility is essential for most clinical pathology and translational cancer research workflows. Confirm that your candidate antibody has been specifically validated for IHC-P.

2. Species Reactivity

Human Ki67 antibodies validated in human samples are not always cross-reactive with rodent tissue. If you are running parallel human and mouse studies, confirm species reactivity for both. Ab15580-type polyclonals have documented reactivity across human, mouse, rat, sheep, rabbit, horse, cow, dog, pig, monkey, and more, making them popular in comparative studies.

3. Detection System Compatibility

The choice between conjugated and unconjugated antibodies depends on your detection platform. Unconjugated antibodies pair with numerous secondary antibodies, giving you flexibility to adapt to different amplification systems (HRP-DAB, Alexa Fluor, tyramide signal amplification, etc.).

4. Validation Data

Prioritize antibodies with knockout-validated specificity. KO cell line validation, demonstrating the absence of signal in MKI67 knockout cells, is the strongest evidence of antibody specificity and guards against off-target staining artifacts.

Human Ki67 Antibody Applications in Clinical and Translational Research

Human Ki67 antibody products are critical tools in translational oncology. The Ki67 labeling index (the percentage of Ki67-positive tumor cells) is used clinically to stratify patients, assess tumor aggression, and guide treatment decisions in breast cancer (particularly luminal B subtype classification), neuroendocrine tumors, gliomas, and lymphomas.

For clinical operations teams working in regulated environments, antibody selection should also account for:

• Instrument platform compatibility (Leica BOND, Ventana DISCOVERY ULTRA, DAKO Omnis)
• Pre-diluted versus concentrate format preferences for automated IHC
• Regulatory documentation and lot traceability requirements

MyBioSource provides detailed specification sheets and certificates of analysis with each Ki67 antibody order, supporting your documentation needs for research and clinical lab workflows.

Ki67 Antibody Cell Signaling and Pathway Context

Ki67 expression is tightly regulated by the cell cycle machinery. During the S phase, Ki67 is diffusely distributed throughout the nucleus. As cells approach mitosis, Ki67 accumulates on chromosomes and is thought to form a perichromosomal layer that may contribute to chromosome condensation and segregation. Understanding this Ki67 antibody cell signaling context helps researchers interpret staining patterns correctly: Nuclear speckled or diffuse staining in actively cycling cells is expected, while the absence of signal indicates G0 arrest or quiescence.

Researchers studying signaling pathways that drive or suppress proliferation, including the CDK4/6-Rb- E2F and mTORC1 pathways, frequently use Ki67 as a functional readout of pathway activity, complementing phospho-protein antibodies with a downstream marker of proliferation.

Why Buy Ki67 Antibodies from MyBioSource?

When you buy Ki67 antibodies from MyBioSource, you get access to a comprehensive catalog with transparent Ki67 antibody specifications, competitive pricing, and the technical details needed to make a confident selection before your order ships.

• Extensive catalog: We stock Ki67 antibodies in monoclonal and polyclonal formats, with host species including rabbit, mouse, and rat, and conjugation options spanning unconjugated, FITC, PE, HRP, Alexa Fluor, and more.
• Validated products: Our antibody listings include application-specific validation data, recommended dilutions, and positive control information, so you can evaluate their suitability before purchase.
• Broad species coverage: Our human Ki67 antibody options are complemented by products validated in mouse, rat, canine, nonhuman primate, and additional species for cross-species experimental designs.
• Detailed documentation: Certificates of analysis, safety data sheets, and lot-specific documentation are available with every order.
• Expert sourcing: As your best Ki67 antibody supplier, MyBioSource maintains relationships with leading manufacturers to ensure consistent product quality and availability for your ongoing research programs.

Frequently Asked Questions

• What is the significance of Ki67 in cell proliferation studies?

  Ki67 is significant in cell proliferation studies because it is expressed only when cells are actively dividing and is completely absent from cells in the resting (G0) phase of the cell cycle. This binary expression pattern makes it one of the most direct and interpretable proliferation markers available. Unlike bromodeoxyuridine (BrdU) or EdU, which require exogenous labeling agents to be administered before tissue collection, Ki67 staining can be performed retrospectively on archival FFPE tissue, a major practical advantage in research and clinical pathology. The Ki67 labeling index (the percentage of Ki67- positive cells in a given tissue) has strong prognostic value in multiple tumor types, particularly in distinguishing low-grade from high-grade neoplasms. In basic research, Ki67 is used to confirm whether experimental treatments (drugs, siRNA, gene edits) are successfully suppressing or inducing cell cycle entry, making it a functional readout in addition to a structural marker.

• Can Ki67 antibodies be used in human and animal studies?

  Yes, many Ki67 antibodies are cross-reactive across multiple species, but reactivity must be confirmed for each specific antibody and application. Polyclonal Ki67 antibodies, such as rabbit polyclonals raised against a human Ki67 peptide sequence, frequently show cross-reactivity with mouse, rat, rabbit, sheep, dog, pig, cow, horse, monkey, and hamster tissue due to sequence conservation of the Ki67 protein across mammals. Monoclonal antibodies are more epitope-specific, and their cross-species reactivity depends on the degree of sequence homology at the target epitope in the species of interest. The SolA15 rat monoclonal clone, for example, has documented reactivity in human, mouse, rat, dog, and nonhuman primate samples, making it a practical choice for comparative or cross-species studies. Always check the product datasheet for confirmed species reactivity and run appropriate positive controls when applying a Ki67 antibody to a species not explicitly listed.

• What are the storage and handling requirements for Ki67 antibodies?

  Storage requirements vary by product format and conjugation, so always follow the manufacturer's datasheet as your primary guide. As a general rule, unconjugated Ki67 antibodies in liquid form (typically in PBS with BSA and sodium azide, or 50% glycerol) should be stored at 4°C for short-term (1–2 weeks) and aliquoted for long-term storage at -20°C. Repeated freeze-thaw cycles are one of the most common causes of antibody degradation; aliquoting upon receipt prevents this. Antibodies formulated with 50% glycerol can often be stored at -20°C without freezing solid, allowing aliquot removal without a full thaw cycle. Fluorochrome-conjugated antibodies (FITC, PE, Alexa Fluor, etc.) should generally be stored at 2–8°C and protected from light; many conjugated formats are sensitive to freezing and should not be stored at -20°C unless the datasheet specifically permits it. HRP-conjugated antibodies should never be stored with sodium azide, as azide inhibits HRP enzymatic activity. For all Ki67 antibody formats, avoid exposure to temperatures above 37°C and minimize time at room temperature during handling.