MAGI3 (Membrane Associated Guanylate Kinase, WW, and PDZ Domain Containing 3): MAGI3 is a scaffolding protein that plays a key role in the assembly of multiprotein complexes at cell junctions and in signal transduction pathways. It is involved in cellular processes such as epithelial cell polarity and may contribute to cancer development, particularly through its roles in cell-cell adhesion and signalling.