The non- or hypo-proliferative state of the dormant ER+ BC cells is initiated by FGF-2 [96,97] and is mediated by increased p21WAF1 [97,98], p27Kip1 and p15INK4b [98] through intracellular TGFβ1 [98], resulting in G1 cyclin complex inhibition and Rb dephosphorylation [97]. This evidence concerns the gene TGFB1 and breast cancer.