Serine/threonine-protein kinase involved in cell autonomous neuroblast asymmetric divisions that generate one precursor cell and one apoptotic cell by controlling spindle positioning, myosin distribution and the segregation of cell fate determinants (PubMed:16774992, PubMed:20929735, PubMed:23946438, PubMed:23267054, PubMed:23851392, PubMed:28659600). Plays a role in neural fate specification in several dopaminergic linages, acting in concert with ham-1 (PubMed:28659600). Involved in phosphorylation of multiple proteins associated with key developmental processes, including the cell cycle, apoptosis, endocytosis, and asymmetric cell division (PubMed:28659600). Promotes cell shedding during embryogenesis, probably through the endocytosis-mediated removal of cell adhesion molecules such as hmp-1 from the cell surface (PubMed:22801495). May act downstream of par-4/strd-1/mop-25 to regulate cell shedding (PubMed:22801495). ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Cytoplasmic in undividing cells and co-localizes with centrosome in dividing cells. Ubiquitously expressed in early embryo with a more restricted expression in later embryonic stages and in young larvae. Expressed in dividing cells including ventral nerve cord neuroblasts, vulval precursors, hypodermal seam cells and in the Q lineage. No expression in adults. The KA1 domain is required for the control of asymmetric neuroblast division. May be phosphorylated at Thr-169 by par-4 and/or autophosphorylated which likely results in its activation (PubMed:22801495). Phosphorylation is not required for co-localization with the centrosome (PubMed:23267054). During neuroblast differentiation, mutants produce an additional precursor cell for the HSN/PHB, I2, M4 and PLM/ALN and Q.a and Q.p lineages. The nucleus size of the 2 Q.p daughter cells is similar (PubMed:16774992). Symmetrical distribution of myosin II during QR.a cell division (PubMed:20929735). Abnormally high number of ADE neurons (PubMed:28659600). Double knockouts of pig-1 and ced-3 have impaired cell shedding during embryogenesis which results in the generation of an ectopic excretory cell and an ERM-like neuron. In addition, mutants show a delay in clearance after engulfment of cell corpses which is associated with the abnormal expression of cell adhesion molecules (PubMed:22801495). Belongs to the protein kinase superfamily. CAMK Ser/Thr protein kinase family. SNF1 subfamily.