an ubiquitous nuclear guanine nucleotide exchange factor (GEF) that activates RAB10. Promotes the exchange of GDP to GTP, converting inactive GDP-bound Rab proteins into their active GTP-bound form. May bind to ISRE-like element (interferon-stimulated response element) of MYC P2 promoter. Highest expression in fetal liver, bone marrow, medium in peripheral blood lymphocytes and lowest in spleen. Induced by serum in low-passage fibroblasts. Expressed at higher levels in normal cells (brain, breast, and prostate) than in tumor cells. Expression is regulated in a growth- and cell cycle-dependent manner. 2 isoforms of the human protein are produced by alternative splicing. Note: This description may include information from UniProtKB.