Figure 6

Western blot indicates changes in GIRK1 protein expression in MDA-MB-453 breast cancer cells 24 and 48 hours after treatment with charcoal-stripped serum ± estradiol. Top panel: C=control; CS=charcoal-stripped; ES=estradiol. These bands are at the lower MW (40–42 kDa) indicated in Figure 1. At 24 hours, GIRK1 levels were increased by charcoal-stripped serum, and were returned to control levels by estradiol. At 48 hours, GIRK1 levels were unchanged by charcoal-stripped serum, and were decreased by estradiol. Bottom panel: Membranes were additionally probed with an antibody for GAPDH to ensure equal loading of protein between samples. In these experiments, estradiol was dissolved in ethanol (1 mM) and diluted in water/culture media. In the control and charcoal-stripped cultures, 10 μl of 1:100 ethanol:water was added, corresponding to the amount of ethanol added to estradiol treated samples. This is a representative gel of two separate experiments. Graph indicates densitometry of bands, and data are shown as a ratio of GIRK/GAPDH.