Required for cytoplasmic partitioning and asymmetric cell division in early embryogenesis. Phosphorylates and restricts the asymmetry effectors mex-5 and mex-6 to the anterior cytoplasm of the zygote and maintains these phosphorylations until fertilization. Phosphorylates and regulates aak-2 in response to oxidative stress. May also play a role in motility, behavioral response, regulation of lifespan and dauer formation through this pathway (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. CAMK Ser/Thr protein kinase family. LKB1 subfamily.