MPP7 (MAGUK p55 scaffold protein 7) is a membrane-associated guanylate kinase family protein that functions as a critical adapter for epithelial cell polarity and tight junction assembly 1. As a member of the MPP gene family with conserved MAGUK domains, MPP7 coordinates protein complex assembly at cell-cell junctions through interactions with polarity-associated proteins including CRB homologs and Lin-7 family members 1. In muscle stem cells, MPP7's L27 domain enhances TAZ-YY1 transcriptional cooperation to regulate genes governing stem cell renewal, including Carm1 2. Functionally, MPP7 inhibits tumor metastasis in clear cell renal cell carcinoma by competing with F-actin to bind α-actinin-4, thereby reducing F-actin polymerization and enhancing Snail degradation through TRIM21-mediated ubiquitination 3. Clinically, high MPP7 expression correlates with improved prognosis in clear cell renal cell carcinoma and associates with pathological stage, grade, and immune cell infiltration 4. Genetic variants in MPP7 show genome-wide significance for bone mineral density variation, with functional studies demonstrating reduced vertebral bone mass in mpp7 knockdown zebrafish models 5. Additionally, MPP7 downregulation under cyclic mechanical stress implicates it in primary open angle glaucoma pathogenesis 6.