Required cell non-autonomously for proper development of the excretory canals and for the long-range anterior-posterior migrations of embryonic neurons CAN, ALM and HSN (PubMed:9142991). Plays a role, probably downstream of ced-10/rac1, in orientating axonal growth of HSN and AVM neurons in response to guidance cues such as slt-1. May regulate growth cone polarization by promoting asymmetric F-actin assembly (PubMed:18499456). May be involved in signal transduction during cell migration (PubMed:9142991).
Required for determination of left/right asymmetry in nervous system. Acts together with unc-40 to control an initial left-right asymmetric polarization of the Q neuroblasts. Mig-21 and unc-40 may control the asymmetry in Wnt signaling response by restricting posterior polarization to one of the 2 Q neuroblasts. Involved in left-side QL posterior migration. In right-side QR, unc-40 and mig-21 pathways mutually inhibit each other in posterior migration, allowing anterior QR migration.
During gonad development, involved in distal tip cell (DTC) migration from the dorsal side of the hermaphrodite body to the midbody which allows for the formation of gonad arms. Role in gonad DTC migration may be in association with integrin related proteins ina-1 and mig-15.