TGFB1 and neoplasm: Although these SCC models induce CAF formation in the primary tumor and we cannot discern the actions of co-transplanted CAFs vs. the actions of newly formed CAFs in the primary tumor or the metastatic microenvironment, the direct conditioning of the lung microenvironment by co-transplanted CAFs to increase lung colonization in a TGFβ-dependent manner suggests that CAF-induced TGFβ signaling is a critical step.