Fig. 1

Effect of DC and other tetracyclines (TC and MIN) on FasL-induced apoptotic cell death. Cells were pretreated with indicated concentrations (0–16 µg/mL) of DC, TC and MIN for 12 h with or without FasL (50 or 100 ng/mL) for 24 h. The metabolic activity was measured by the MTT assay. Each point represents the mean ± SEM (n = 3). a Effect of DC on FasL-induced cell viability in HeLa cells. b Effect of DC on FasL-induced cell viability in NIH3T3 cells. c Effect of TC on FasL-induced cell viability in HeLa cells; d effect of MIN on FasL-induced cell viability in HeLa cells. The significance was determined by Student’s t-test (n = 3). ^# p < 0.05, compares with control group. *p < 0.05 and p < 0.01, compared with FasL treated groups. DC doxycycline, TC tetracycline, MIN minocycline.