The epidemiological positive correlation between cigarette smoking and liver cancer has been demonstrated in previous studies.9 Among different subtypes of nicotinic receptors, α7nAChR is one of the highly expressed receptors in the liver.4 In the present study, the effect of nicotine on the viability of cultures of HepG2 cells was analyzed and we provide functional evidence that nicotine induced proapoptotic gene caspase-3 expression and increased apoptosis through the α7nAChR in HepG2 cells (Figure 6). This evidence concerns the gene CASP3 and liver cancer.