CDKN1B and breast cancer: Similarly, 4-hydroxytamoxifen (but not tamoxifen), genistein and daidzein (but not genistin), resveratrol, retinoic acids (e.g., all-trans, 9-cis, and 13-cis) and dexamethasone up-regulated expression of p27 in estrogen receptor-negative MDA-MB-231 human breast cancer cells in vitro [10].