Supplemental Fig. 1 Fig. S1. Requirement for both ALA treatment and irradiation to elicit a stress response. PC3 cells in serum-free medium were dark-incubated in the presence of 1 mM ALA for 30 min, than washed, and either not irradiated or irradiated (light fluence: 1 J/cm2). After removal of the medium and replacement with 10% serum-containing Medium, the cells were dark-incubated for 24 h, after which the viable cell titer was determined by MTT assay. Plotted data are relative to a non-ALA/light-treated control; values are means ± SEM (n=3).