Detection of apoptotic BT474 cells by annexin V staining and sub-G
DNA peak analysis. BT-474 cells were either untreated or treated with vehicle (ethanol + PBS), 1 μM all-trans retinoic acid (atRA), 1 μg/ml trastuzumab, 1 μM tamoxifen, 1 μM atRA + 1 μg/ml trastuzumab (Tzmab), 1 μM atRA + 1 μM tamoxifen (Tam), 1 μg/ml trastuzumab (Tzmab) +1 μM tamoxifen (Tam), or 1 μM atRA + 1 μg/ml trastuzumab (Tzmab) + 1 μM tamoxifen (Tam). On days 2, 4, and 6 following treatment, both floating and adherent cells were collected and examined by (a) annexin V staining or (b) sub-G1 DNA peak analysis. Percentages of (a) annexin V-positive cells or (b) cells in the sub-G1 DNA peak were determined by flow cytometry. Results are mean of three independent experiments ± standard error.