MACROD2 overexpression in human breast cancer cell lines mediates tamoxifen resistance and growth. (A) Whole cell lysates were harvested from cell lines as indicated and used for Western blots. EV, empty vector control. GAPDH antibody staining was used for a loading control. (B) MCF-7, T47D and their derivate cell lines were seeded in assay media and exposed to vehicle (ethanol) or 1 μM 4-OH tamoxifen for 7 d as described in the text. EV, empty vector control. *P < 0.01. (C) MCF-7 and the derivative cell lines were seeded in triplicate and exposed to estrogen (1.25 nM 17-β-estradiol), tamoxifen (1 μM 4-OH tamoxifen), or a combination of both drugs for 7 d as described in the text. EV, empty vector control. *P < 0.01.