Figure 4. qPCR analysis demonstrated impaired induction of cell-cycle-related genes. (A) Impaired gain of liver weight in aged mice after APAP injury. Liver/body weight gradually increased in young mice after APAP administration, whereas it is once decreased at 24 hours after the injury and then recovered to the original ratio at 48 hours in aged mice. The difference of liver/body weight between young and aged mice is statistically significant at 24 and 48 hours. The graph shows average values with SEMs. (B) Expression analysis for genes involved in cell cycle progression. Foxm1b, Cdk1, and Ccnd1 are upregulated at 48 hours after APAP injury in young livers but not in aged ones. The graph shows average values with SEMs.