**Figure 4. **Viability of human trabecular meshwork (hTM) cells. **A**:SA-2 dose-dependently increased the number of viable hTM cells and exhibited no toxicity up to 125 µM. The half maximal effective
concentration (EC_{50}) was calculated to be 53.5 µM. **B**: SA-2 dose-dependently increased the number of viable hTM cells in the presence of *tert*-butyl hydroperoxide (TBHP, 300 µM). The EC_{50} was calculated to be 0.38 µM. **C**: SA-2 dose-dependently protected hTM cells against TBHP (300 µM) and induced cell proliferation up to the 16 µM dose. hTM
cell viability is represented as % of control. Experiments were performed in triplicate with n = 4 technical replicates. Values
are expressed in mean ± standard error of the mean (SEM). *p<0.01, one-way analysis of variance (ANOVA).