FIGURE 4.

Effect of estrogen on mechanical stress induced apoptosis of hUSLFs occurs in a dose-dependent manner. (A) Representative dot plots of cell apoptosis by flow cytometry analysis after Annexin V/7-AAD dual staining. The apoptotic rate was determined as the percentage of 7-AAD negative and Annexin V positive (Q3). Cells that are already dead are both Annexin V and 7-AAD positive (Q2). (A,D) 0 M estrogen treatment; (B,E) 10⁻¹⁰ M estrogen treatment; (C and F) 10⁻⁹ M estrogen treatment. (G) Quantified apoptotic rates of hUSLFs treated with various concentrations of estrogen for 24 h, 0.5 Hz, 20% strain. (H) Quantified dead rates of hUSLFs treated with various concentrations of estrogen for 24 h, 0.5 Hz, 20% strain. Values are expressed as the mean ± standard deviation of three independent experiments. *p < 0.05; **p < 0.01 vs. control.