GRID2IP (Grid2 interacting protein) is a postsynaptic scaffolding protein at the parallel fiber-Purkinje cell synapse 1. As a non-FDD-type formin homology protein, GRID2IP contains PDZ, GRCAH, FH1, and FH2 domains that enable it to link the glutamate receptor delta2 subunit (GRID2) with the actin cytoskeleton and various signaling molecules 1. The protein plays a regulatory role in actin filament assembly and cell polarity control 1. Human GRID2IP maps to chromosome 7.1 and shows high conservation with mammalian orthologs (91.7% identity with rat Grid2ip) 1. Beyond its established neuronal function, emerging evidence suggests GRID2IP involvement in cancer biology. GRID2IP is upregulated in colorectal cancer (CRC) patients, where elevated expression correlates with poor prognosis across multiple clinical subgroups 2. High GRID2IP expression inhibits tumor-associated immune cell infiltration and reduces immune score, suggesting immunosuppressive properties 2. Additionally, low-frequency variants within GRID2IP are significantly associated with factor VIII inhibitor development in hemophilia A patients, implicating an unrecognized role in autoimmunity 3. These findings indicate GRID2IP may serve as a biomarker for CRC prognosis and a potential therapeutic target, warranting further investigation into its extraneuronal functions.