(a) Total photon flux, integrated over 2 h, from PC3M-luc cells with D-cysteine (100 μM) added 0, 15, 30, 45, or 60 min after incubation with HCBT (100 μM). (b) Representative image of PC3M-luc cells with D-cysteine added 0, 15, 30, 45, or 60 min following removal of HCBT. (c) Total photon flux, integrated over 2 h, from PC3M-luc cells with HCBT (100 μM) added 0, 15, 30, 45, or 60 min after incubation with D-cysteine (100 μM). (d) Representative image of PC3M-luc cells with HCBT added 0, 15, 30, 45, or 60 min following removal of D-cysteine. Error bars are ±SEM; A and C: n = 3.