Required for formation of the pseudocleavage furrow during the first cleavage of the embryo and also mediates aster-induced furrowing during cytokinesis. Promotes cortical recruitment of ani-1 and nmy-2 during pseudocleavage and cytokinesis and promotes the accumulation of actin at furrowing regions. Regulates establishment of embryonic cell polarity. Highly concentrated in interphase nuclei. As well as a significant cytoplasmic pool, a distinct cortical localization is also detected, particularly at ingressing pseudocleavage and cleavage furrows. Mutant embryos do not display the anterior cortical contractions associated with pseudocleavage and do not form a pseudocleavage furrow. Cortical actin foci remain uniformly distributed rather than the asymmetric distribution seen in wild-type embryos. Approximately 20% of mutant embryos fail to hatch. Those that do hatch are viable and fertile and display normal P granule localization. Increased embryonic lethality in par-1, par-2 and par-3 mutants.