Figure 3: Impact of transsulfuration inhibition (PPG) on cellular total glutathione levels in human mammary epithelial cells subjected to oxidative challenge (H2O2). Human mammary epithelial cells (HMEC’s) were grown in normal mammary epithelial growth medium to 50% confluency and pretreated with a PBS vehicle control or propargylglycine (PPG) for 24 hours, followed by treatment in the same media with vehicle or 300 uM H2O2 for two hours. Cell pellets were prepared and analyzed for total glutathione levels as described under methods [45]. Results are expressed as nmol/mg of cell protein (mean ± SEM, -6). Asterisk indicates a significant difference between PBS/H2O2 and PPG/H2O2 groups determined by ANOVA ( ).