TGFB1 and neoplasm: In contrast to Transwell assays using fibroblast conditioned medium (showing that both TGF-β1 and irradiated myofibroblasts secrete factors that promote tumor cell migration; Fig. 2J), tumor cells showed significantly increased invasion only through matrices secreted by TGF-β1-treated fibroblasts (Fig. 5C), suggesting that this ECM differentially promotes cancer cell invasion.