When cross-linked to form dimers and trimers, it has a regulatory effect on ERK signaling pathway activity in response to EGF stimulation. Colocalizes with the EGF receptor in WDR54-specific vesicle where it sustains the internalization and controls the degradation of the EGF receptor after EGF stimulation. Homodimer and homotrimer; forms tight forms of dimers and trimers. Aggregates in vesicles when cross-linked. WD6 repeat is required for cross-linking by TGM2. Cross-linked to tightly form both dimers and trimers by TGM2. Cross-linking enhances the activation of EGF receptor-mediated signaling pathway. Cross-linking is inhibited by EGF. Ubiquitinated. EGF increases ubiquitination.