TGFB1 and breast cancer: BMP signaling pathway has been shown to have an antagonistic role to TGF-β/activin signaling in various physiological and pathological conditions.37,38 In addition, recent studies have shown that BMP signaling has a tumor-suppressive function in cancers.39 Hence, hyperactivation of activin-A signaling and loss of BMP signaling may have a critical role in the clinical outcome of breast cancers.