A Rho1-GTP sensor localizes minimally to caps and is not promoted by Par-1. (A) The Rho1-GTP sensor Anillin-RBD-GFP enriched at actomyosin borders of control embryos, and with RhoGEF2 RNAi (observed in 15/15 control RNAi embryos and 12/14 RhoGEF2 RNAi embryos [combined data of two shRNA constructs] at cycle 11). (B) Rho1-GTP sensor detected at bundle-like structures of early caps (arrows) in controls, but its levels were higher in actomyosin borders. With furrow ingression, signal reduced in caps and increased in actomyosin borders. par-1 RNAi did not diminish the Rho1-GTP sensor signal (observed in 5/5 par-1 RNAi embryos compared with the controls). With par-1 RNAi, the sensor signal seemed spatially disorganized and elevated. Time = 0 is arbitrary. Genotypes begin at the same stage. Time given in minutes and seconds.