RAC1 and breast cancer: Although direct interaction between Rac1 and WAVE2 is not detected in human breast cancer cells, Rac1 forms a complex with CLIP-170, a microtubule-binding protein [70, 71], an actin cross-linking protein IQGAP1 [33, 34], and kinesin-1, one of the major motor proteins [72, 73], under the growth-arrested conditions [74] (Figure 1(a)).