2A. c-Src phosphorylation changed after short-term absence of E2 in ER positive wild-type cells. Wild-type ER positive cells were cultured under conditions with basal estrogen (10% FBS) or without basal estrogen (10% SFS) for 3 days, respectively. Cell lysates were harvested. Phosphorylated c-Src was examined by immunoblotting with primary antibody. Immunoblotting for total c-Src was determined as loading control. 2B. Growth inhibitory effects of PP2 on ER positive wild-type cells under conditions with or without basal E2. Wild-type ER positive cells were cultured under conditions with basal estrogen (10%FBS) or without basal estrogen (10% SFS) for 3 days, respectively. Then, they were seeded in 24-well plates in triplicate. After one day, the cells were treated with vehicle (0.1%DMSO) and PP2 (5μM) in estrogenized medium (10%FBS) or E2 free medium (10%SFS), respectively. The cells were harvested after 7 days treatment and total DNA was determined as above. 2C. The PP2 had different effects on E2 stimulation in ER positive wild-type cells. Wild-type ER positive cells were changed to E2 free medium for 3 days. Then, they were seeded in 24-well plates. After one day, the cells were treated with vehicle (0.1% EtOH), E2 (10−9 mol/L), PP2 (5μM), and E2 (10−9 mol/L) plus PP2 (5μM) respectively in E2 free culture medium. The cells were harvested after 7 days treatment and total DNA was determined as above.