RhoA regulates myosin regulatory light-chain phosphorylation and microtubule organization during erythroblast cytokinesis. (A) Myosin regulatory light-chain phosphorylation is decreased in E14.5 RhoA^Δ/Δ fetal liver cells as shown by western blotting. (B) RhoA colocalizes with β-tubulin in WT erythroblasts undergoing mitosis, possibly participating in the formation of the microtubule-derived midbody structure observed in cytokinesis. The nuclear stain DAPI was used to indicate the nucleus. Four representative cells are shown of at least 30 dividing cells with similar morphology. Images were obtained with a 60× objective lens by ImageStream^X. (C) Citron kinase was significantly decreased in E13 RhoA^Δ/Δ Ter119⁺ fetal liver cells, as shown by capillary electrophoresis and immunodetection.