HACE1 and cancer: In breast cancer, Rac1 has been reported to be overexpressed and hyperactive.18 Upon activation by guanine nucleotide exchange factors (GEFs), active (GTP-bound) Rac1 has been shown to increase cancer cell migration, proliferation, transcription and survival by activating a multitude of downstream effectors.19 To determine whether HACE1 controlled Rac activation in breast cancer cells, HACE1 was overexpressed in MCF7 breast cancer cell line (Figure 3c).