RABGAP1L (RAB GTPase activating protein 1-like) is a TBC-domain-containing GAP protein that regulates small GTPase signaling in endosomal trafficking and cell-autonomous immunity. As a GTPase-activating protein, RABGAP1L catalytically inactivates multiple Rab GTPases including RAB22A, RAB7A, and RAB10, converting them from their active GTP-bound to inactive GDP-bound states 1. The protein functions as part of an ANK2/RABGAP1L complex recruited to phosphatidylinositol 3-phosphate-positive early endosomes, where it promotes polarized recycling of α5β1-integrin to enable directional cell migration 2. During pathogenic infections, RABGAP1L modulates cell-autonomous immune responses by inactivating RAB7A and RAB10 to coordinate selective autophagy against Group A Streptococcus with bacterial expulsion via endocytic recycling pathways 3. The protein also potentiates interferon-mediated antiviral defense by disrupting endosomal function and restricting early-stage entry of influenza A virus and other endocytosis-dependent RNA viruses 4. Clinically, RABGAP1L deletions associate with systemic lupus erythematosus risk in a dose-dependent manner 5, and altered RABGAP1L expression correlates with colon cancer prognosis 6. These findings establish RABGAP1L as a critical regulator linking endosomal trafficking to both adaptive and innate immunity.