Figure 1: Different growth responses to E2 between wild-type MCF-7 and MCF-7:5C cells. Wild-type MCF-7 cells were first transferred to E2-free medium for 3 days. Then, MCF-7 and MCF-7:5C cells were loaded in 24-well plate respectively. After one day, cells were treated with different concentrations of E2 as indicated. Cells were harvested after 7 days treatment. Cell viability was quantitated by determination of total DNA.