Has a role in the septation initiation network (SIN) required for cytokinesis. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Interacts with cdc14. Localizes to the SPB prior to cytokinesis and leaves once septation is complete. Belongs to the protein kinase superfamily. STE Ser/Thr protein kinase family. STE20 subfamily.