The impact of heightened TGF-β secretion has been shown in several experiments with rodent gland-free mammary fat pad assays, where tumor induction was shown to be dependent on either activated fibroblasts or carcinogenic treatment of the stroma before implantation of non-tumorigenic epithelial cells [[50], [51], [52], [53]]. This evidence concerns the gene TGFB1 and neoplasm.