Detection of apoptotic BT474 cells or SKBR3 cells treated with various retinoid combinations, determined by sub-G
DNA peak analysis. (a) BT474 cells or (b) SKBR3 cells were either untreated or treated with vehicle (ethanol + PBS), trastuzumab (Tzmab), various retinoids, or their combinations. On day 6 following treatment, both floating and adherent cells were collected and examined by sub-G1 DNA peak analysis. Percentages of cells in the sub-G1 DNA peak were determined by flow cytometry. Results are mean of three independent experiments ± standard error. atRA, all-trans retinoic acid; 4-HPR, N-(4-hydroxyphenyl) retinamide (fenretinide); RA, retinoic acid.