The authors conclude that conserved residues across EGFR family members drive a shared activation mechanism. Sequence alignment reveals that HER2 and HER4, like EGFR, are autoinhibited and activated though the same asymmetric dimeric configuration, while ErbB3, lacking catalytic activity, likely functions as cyclin-like activator for its relatives. Structurally, their crystallographic findings show that this activation mirrors the CDK-cyclin mechanism, where dimerization relieves inhibition to restore catalytic function. Overall, the study defines a coherent model that sets out how EGFR and its homologues adopt an intrinsic allosteric switch to control activation, each effectively serving as its own “cyclin.”