Fig. 3. RGA-3 and RGA-4 are RhoGAPs for RHO-1 and not for CDC-42. (A-D) Epistasis RNAi experiments of rho-1 (A), cdc-42 (B), ect-2 (C) or let-502 (D) with or without rga-3 and rga-4 (rga-3/4) were performed by feeding with the RNAi construct in question either alone, or by mixing together the same amounts of bacteria containing the rga-3/4 construct or RNAi construct being studied and feeding these at the same time. In the case of LET-502, epistasis experiments were also performed with the let-502(ok1283) allele, which is a knockout of LET-502. (A) Concomitant knockdown of RGA-3/4 and RHO-1 led to a catastrophic one-cell arrest, similar to rho-1 RNAi treatment [rho-1(RNAi)]. (B) cdc-42(RNAi) did not rescue the rga-3/4(RNAi) phenotype. The knockdown of the RhoGEF ECT-2 (C) and the Rho-associated kinase LET-502 (D) rescued the rga-3/4(RNAi) phenotype. Nuclei were visualized with GFP::H2B. Scale bars: 20 µm.