Protein kinase required for the cell cycle where it is involved in mitotic exit. Required to form a bipolar spindle, the actin ring and septum. Functions upstream of the whole septum formation pathway, including actin ring formation (regulated by late septation genes) and septal material deposition (regulated by early septation genes). Behaves as a 'septum-promoting factor', and could also be involved in inducing other late events of cell division (By similarity). ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Belongs to the protein kinase superfamily. Ser/Thr protein kinase family. CDC5/Polo subfamily.