Effects of CSE on Phase I detoxification genes. HCMEC/D3 cells were exposed to nicotine or CSE from different products (see “Methods”). Effects of CSE and nicotine on NQO-1 mRNA and protein expression were characterized by: a1 gene array analysis; a2 real-time RT-PCR; b immunofluorescence and western blot analyses of NQO-1 protein. Representative western blots were shown with actin as a loading control. Data were expressed as mean ± SEM (fold change over control). *p < 0.05, **p < 0.01, ****p < 0.0001 vs. control. n = 6/biological replicates/condition.