The function of Ensembl gene identifier ENSG00000124126 (PREX1, phosphatidylinositol-3,4,5-trisphosphate dependent Rac exchange factor 1) is as follows. 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.