The effect of ROCK and Rac1 inhibitors on adhesion to endothelial cells in vitro and extravasation and homing in vivo. (A) The effect of ROCK and Rac1 inhibitors on SDF1-induced MM1S cell adhesion to plates coated with HUVEC cells in vitro showing that both inhibitors reduced the adhesion with no additive effect for the combination. (B) The effect of ROCK and Rac1 inhibitors on MM1S cell homing after tail vein injection in mice detected by detection of circulating MM1S cells with time showing that both inhibitors reduced the adhesion with no additive effect for the combination. (C) The effect of ROCK and Rac1 inhibitors on MM1S cell homing to the BM niches in mouse skull after tail vein injection demonstrating that both inhibitors prevented homing of MM1S cell to BM, whereas ROCK inhibitor had a more profound effect. (D) Quantification of the number of MM1S cell homed to BM in panel C. (E) The suggested mechanism for SDF1-induced MM cell adhesion and chemotaxis involving RhoA and Rac1. Panel A: Groups compared with the SDF1-treated group. Panel D: Groups compared with the control, *P < .05; #P < .01.