TGFB1 and neoplasm: Despite ERK5 is a well-established mediator of TGF-β-elicited epithelial-to-mesenchymal transition (EMT), a clear tumor-promoting feature (see the section “Activating Invasion and Metastasis”), there is no evidence of a possible role of ERK5 in the regulation of TGF-β-elicited growth-suppressive effects.