EGFR and cancer: The EGFR has become oneof the most extensively studied cell surface receptors and a majoroncogenic drug target, as aberrant receptor activation and intracellularsignal transduction is associated with a variety of cancers, thusmaking its key players in downstream signaling to the perfect proofof concept target for our study.23 We couldunequivocally show that EGFR downstream signaling is based on Grb2-mediatedternary protein complexes exhibiting different interaction regimes(constitutively bound vs agonist-dependent).