Figure 1

Treatment of MCF-7 cells with 4-OH Tam resulted in a resistant phenotype. A. Survival ratio vs time (zero to six months). MCF-7 cells cultured with 10^-7 M 4-OH tamoxifen for zero to six months were plated in six-well plates at a density of 50,000 per well in 5% FBS DMEM medium. The cells were counted after treatment with 10^-7 M 4-OH tamoxifen for five days; the final concentration of ethanol was 0.1%. B. Survival ratio vs 4-hydroxytamoxifen concentration. MCF-7 cells cultured for six months with 10^-7 M 4-OH tamoxifen (MCF-7-TamR) and 0.1% ethanol (MCF-7-control) were seeded in 96-well plates at a density of 3,000 each in 5% FBS phenol-red free DMEM medium. The cells were then treated with 10^-7 to 10^-5 M 4-OH tamoxifen for five days.