RAP-2-independent roles for C. elegans MIG-15

MIG-15 is the sole Caenorhabditis elegans member of the GCK-IV subfamily of Ste20 kinases. In mammals and in vitro , MIG-15-like kinases can function as effectors of the small GTPase Rap2. To test this model in vivo , we compared phenotypes of mig-15 and rap-2 mutants. mig-15 mutants displayed severe defects in vulval morphogenesis, cell positioning, and locomotion. In contrast, rap-2 mutants were largely indistinguishable from wild type. These findings indicate that several developmental roles of MIG-15 occur independently of RAP-2, suggesting that additional upstream regulators, including other small GTPases or adhesion-related pathways, control MIG-15 activity in specific developmental contexts.