GST P1-1 protects tumor cells against toxicity and apoptosis following cis-DDP treatment. (A) Cell viability of SH-SY5Y cell lines expressing WT and mutated GST P1-1, after cis-DDP administration. MTS assay was performed on cells treated with 5 µM cis-DDP for 24 h. Values, normalized to untreated control cells, are expressed as means ± SD from 3 independent experiments. Statistical significance compared with untreated samples (Student’s t test): *P < 0.05, **P < 0.01, ***P < 0.001. SH-SY5Y, nontransfected cells; −, cis-DDP–negative samples; +, after exposure to cis-DDP 5 µM for 24 h. (B) FACS analysis of apoptosis induction of SH-SY5Y cell lines expressing WT and mutated GST P1-1, after cis-DDP administration for 24 h. Values are expressed as means ± SD from 6 independent experiments; *P < 0.05. (C) Cytofluorometric analysis of apoptosis induction of SH-SY5Y cell lines expressing WT and mutated GST P1-1, after cis-DDP administration for 6 h followed by a recovery for additional 24 h. Values are expressed as means ± SD from 6 independent experiments; *P < 0.05.