TGFB1 and neoplasm: Notably, this switching of TGFβ to a pro-proliferative factor in the presence of high PEAK1 levels correlates with PEAK1’s ability to promote TGFβ-induced motility, EMT gene expression, mesenchymal cell morphology and tumor metastasis (Figs 2, 3, 4 and 5 and S6 Fig).