GSH depletion in cultured cells and prostate cell lysates treated with S-NPAA. A) LNCaP, RWPE-1, COS-7, and COS-7-OPH cell cultures were incubated with 25 μM S-NPAA for 30 min followed by a 30 min incubation with CMAC. The blue fluorescence indicates the presence of GSH. B) Microscopy images were analyzed with ImageJ to measure the relative fluorescence between cell lines. Percent area threshold was defined as the percent area of fluorescence that exceeded background; *indicates that the treatment was significantly different from control (vehicle) at P < 0.05. C) A reaction mixture containing reduced GSH, S-NPAA, and 90 μg of indicated cell lysate. At each indicated time point, the amount of reduced GSH was measured as described in the Methods Section. The results were normalized to a control without lysate. Data points marked with letters that are not the same are significantly different at p < 0.05.