Ser/Thr kinase required for wild-type filamentous growth, chlamydospore formation, and virulence in mouse systemic infection. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Interacts (via the CRIB domain) with CDC42. The CRIB domain is involved in the interaction with CDC42. Leads to defects in morphology and hyphal formation, impaired chlamydospore formation, reduced colonization of the kidneys in infected mice and suppressed virulence in the mouse model. Belongs to the protein kinase superfamily. STE Ser/Thr protein kinase family. STE20 subfamily.