RAC1 and neoplasm: Rac3 and Rac1 have opposite effects in PC-3 prostate tumor cell diapedesis; while depletion of Rac1 inhibits diapedesis, Rac3 knockdown promotes diapedesis, showing that Rac1 is required for PC-3 cell diapedesis across a bone marrow endothelial cell layer, while Rac3 inhibits tumor cell diapedesis [68].