Functions as a guanine nucleotide exchange factor (GEF) with specificity for RAB11A and RAB25 (PubMed:26506309, PubMed:30217979). Inhibits the auto- and transphosphorylation activity of BTK. Plays a negative regulatory role in BTK-related cytoplasmic signaling in B-cells. May be involved in BCR-induced apoptotic cell death.
