Protein kinase that may play an important role in cellular stress response. May be involved in the regulation of processes such as cell survival, neuronal excitability and renal sodium excretion (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. AGC Ser/Thr protein kinase family.