Arhgef4 acts as guanine nucleotide exchange factor (GEF) for RHOA, RAC1 and CDC42 GTPases. Binding of APC may activate RAC1 GEF activity. The APC-ARHGEF4 complex seems to be involved in cell migration as well as in E-cadherin-mediated cell-cell adhesion By similarity. It is required for MMP9 up-regulation via the JNK signaling pathway in colorectal tumor cells. Arhgef4 is involved in tumor angiogenesis and may play a role in intestinal adenoma formation and tumor progression.