(A) Schematic depiction of the known regulators of RhoA. (B) Representative embryos demonstrating the effect of RGA-3/4 depletion on cytokinesis in CYK-4R459A embryos both in the presence and absence of NOP-1 function. (C) Depletion of RGA-3/4 rescues cytokinesis specifically in CYK-4R459A embryos. CYK-4∆C1, CYK-4EE, CYK-4R459A where expressed in nop-1(it142) embryos and the extent of furrow closure measured either in the presence (green) or the absence (red) of RGA-3/4. (D) Accumulation of the RhoA effector NMY-2 (tagged with RFP) in embryos of the indicated genotypes. Embryos are shown at ∼50% (or maximal) ingression. Note the reduction of cortical myosin accumulation in CYK-4R459A, CYK-4EE, CYK-4∆C1 embryos as compared to CYK-4WT (i–iv). The severity of this reduction is enhanced by inactivation of NOP-1 (i′–iv′). Depletion of RGA-3/4 restores myosin accumulation in CYK-4R459A and CYK-4EE embryos (v, vi), even in embryos defective in NOP-1 function (v′, vi′). (E) Quantification of total NMY-2::mRFP accumulation in the furrow region over the course of cytokinesis in embryos of the indicated genotypes. Error bars, s.e.m.; n.s. (not significant); #p < 0.05; ###p < 0.001 refers to significance relative to wild-type in nop-1(+) and nop-1(it142), respectively by one way ANOVA followed by Tukey multiple comparison. ***p < 0.001 for the indicated comparison.