RAC1 and breast cancer: TRIO, a member of the HCCS24 gene set (Figures 3, genes above the blue line), is a guanine nucleotide exchange factor (GEF) that activates RAC1 (Figure 11, interaction 12) and stimulates the invasive behavior of some glioblastoma and breast cancers; inhibitors of this action of TRIO have been developed [32]–[33].