Involved in cell migration and signal transduction (PubMed:11967148, PubMed:22732572). Important in several developmental processes including epidermal development, Q neuroblast migrations and muscle arm targeting. Required with ina-1/pat-3 to stabilize the commissural axons growth cone along a precise direction and are required for the cell to respond appropriately when signaling in the growth cone must change (PubMed:11967148). During gonad morphogenesis, involved in distal tip cell (DTC) migration from the dorsal side of the hermaphrodite body to the midbody to allow for formation of gonad arms (PubMed:22732572). ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Mutants exhibit premature branching of commissures (PubMed:11967148). RNAi-mediated knockdown results in gonad distal tip cell (DTC) migration defects whereby DTCs do not migrate to the midbody of the hermaphrodite and as a consequence this leads to abnormal gonadal arm formation during gonad morphogenesis (PubMed:22732572). Double knockdown with mig-38 results in enhanced gonad DTC migration defects (PubMed:22732572). Belongs to the protein kinase superfamily. STE Ser/Thr protein kinase family. STE20 subfamily.