Functions as a RAC guanine nucleotide exchange factor (GEF), which activates the Rac proteins by exchanging bound GDP for free GTP. Its activity is synergistically activated by phosphatidylinositol 3,4,5-trisphosphate and the beta gamma subunits of heterotrimeric G protein. May function downstream of heterotrimeric G proteins in neutrophils (By similarity). Interacts preferentially with RAC2 (PubMed:16243036). Interacts with RAC1 (PubMed:16243036). Interacts with AUTS2 (PubMed:25533347). Mainly cytosolic. Some amount is apparently associated to the plasma membrane (By similarity).