Abstract
<jats:p>How growth factor receptors decode ligand identity into distinct cellular responses remains a fundamental question in cell signaling. Here, we identify a receptor-proximal mechanism that links ligand-specific EGFR activation to distinct endocytic and biological outputs. We show that EGF, but not TGF[alpha], selectively engages a RAC1-PLC[gamma]2-IP3R signaling axis that supports EGFR non-clathrin endocytosis (NCE). PLC[gamma]2, but not PLC[gamma]1, localizes to RTN3-dependent PM-ER contact sites, where it generates localized Ca2+ signals required for completion of NCE, mitochondrial activation and cell motility. This specificity requires the RAC-binding interface of PLC[gamma]2 and is associated with RAC1-dependent formation of CTxB-positive PM regions, indicating that spatial organization contributes to signaling specificity. TGF[alpha] fails to efficiently assemble the EGFR-associated organelle platform and instead favors clathrin-dependent EGFR uptake, prolonged proliferative signaling, greater organoid yield, and reduced migration compared with EGF. Together, our findings identify the RAC1-PLC[gamma]2 axis as the key determinant that decodes EGFR ligand bias by coupling receptor trafficking to the metabolic program that supports cell migration.</jats:p>