Figure 1.

Characterization of MCF-7 derivatives with acquired resistance to fulvestrant. A. The parental MCF-7 cells and its derivatives with acquired fulvestrant resistance (ICI-R) were inoculated in 96-well plates and treated with Fulvestrant of indicated doses or mock treated for 72 h. Cell growth was evaluated by MTT assay. The results are presented as mean ± SD based on three independent experiments. *, P < 0.05, **, P < 0.01, ***, P < 0.001 as determined by t-test. B and C. The levels of indicated endogenous proteins were analyzed by western blotting using the designated antibodies. β-actin was used as the internal controls. Expression of ErbB2/HER2 in BT474 was used as the positive control of HER2 expression.