Acts as a positive regulator of apoptosis. Phosphorylates myosin light chains. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Interacts with CHP1; the interaction induces CHP1 to translocate from the Golgi to the nucleus. Colocalizes with STK17B at the plasma membrane. Highly expressed in thymus, spleen, and testis, lower levels present in the brain. Autophosphorylated. Belongs to the protein kinase superfamily. CAMK Ser/Thr protein kinase family. DAP kinase subfamily.