Silencing of CDC42 with two independent siRNAs strongly impaired the formation of invadopodia and collagen degradation by MDA-MB-231 cells (Fig. 5, A and B; Fig. S2 D; and Fig. S3 D), confirming that CDC42 is a master regulator of invadopodia formation and activity in cancer cells (Ayala et al., 2009; Di Martino et al., 2014; Sakurai-Yageta et al., 2008; Yamaguchi et al., 2005). Here, CDC42 is linked to cancer.