Delays the mitotic G2/M transition by promoting nuclear exclusion of cdc25 (PubMed:15629716, PubMed:12080074). During osmotic stress, inhibits the G2/M transition in a sty1 stress-activated MAPK pathway-dependent manner (PubMed:15629716, PubMed:12080074, PubMed:12589433). ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Translocates from the cytoplasm to the nucleus during environmental stress in a sty1-dependent manner. Induced during environmental stress. Phosphorylated by sty1. Decreases the interaction between rad24 and cdc25 (PubMed:15629716). Small cells at septation (PubMed:15629716). Sensitive to osmotic stress (PubMed:15629716). Belongs to the protein kinase superfamily. CAMK Ser/Thr protein kinase family. CaMK subfamily.