During early embryogenesis, controls asymmetric cell division and the asymmetric localization of P granules of germline precursor P2 and its descendant P3 (PubMed:7555722). Probably upstream of tyrosine kinase src-1, plays a role in endoderm development by controlling spindle orientation during EMS blastomere cell division (PubMed:12110172). Controls EMS spindle orientation probably by promoting lin-5 and gpr-1/2 enrichment at, and let-99 exclusion from the junction between P2 and EMS cells (PubMed:14534135, PubMed:12730122). Localizes at the site of contact between EMS and P2 cells in the 4-cell stage embryo, between P3 and E cells in the 12-cell stage embryo and between P4 and Ep cells in the 26-cell stage embryo. Expressed at least in P2 germline cell at 4-cell stage and up to 26-cell stage embryos (PubMed:11003841, PubMed:12110172). Expressed only at L4 stage during larval development and then accumulates in adults (PubMed:11003841). The protein kinase domain is predicted to be catalytically inactive. 71 percent of embryos of mutant mothers develop into sterile adults with extra body muscle cells at the restrictive temperature (25 degrees Celsius) (PubMed:7555722). Low embryonic lethality (7-8 percent) (PubMed:7555722). Loss of lin-5 and grp-1/2 enrichment at the EMS/P2 cell boundaries at the 4-cell embryonic stage (PubMed:12730122). Decrease in phosphotyrosine levels at the site of contact between P2 and EMS cells (PubMed:12110172). Belongs to the protein kinase superfamily.