May be a transforming oncogene with exchange activity for CDC42 (By similarity). May be a guanine-nucleotide exchange factor (GEF) for RAC1 and CDC42. Activated by the binding to subunits beta and gamma of the heterotrimeric guanine nucleotide-binding protein (G protein) (PubMed:18045877). Involved in the regulation of actin polymerization (PubMed:26573021). The disease is caused by variants affecting the gene represented in this entry. Extended N-terminus.