RAC1 and melanoma: Decreasing the contractility of the endothelial cells by treatment with the actin polymerization inhibitor cytochalasin D, the non-muscle ATPase inhibitor blebbistatin44, the MLCK inhibitor ML-745, the Rac1 inhibitor NSC23760, or the ROCK inhibitor Y2763246 abrogated A2058 melanoma cell-induced gap formation between endothelial cells (Fig. 2D).