Down-regulated ARPP-19 resulted in decreased phosphorylated mitotic substrates. (A) The protein levels of ARPP-19, cyclin A, cyclin D1, cyclin B1, Cdk2 and Cdk4 in HepG2 or SMMC-7721 cells were analyzed by western blot, with β-actin serving as an internal reference; (B) HepG2 or SMMC-7721 cells were synchronized at the M phase by thymidine and released into nocodazole for 16 h. The protein levels of ARPP-19, phospho-cdc2 (Tyr15) and the phosphorylation of the different cyclin B-Cdc2 substrates (phospho-(Ser) CDKs substrate) were analyzed by western blot, with β-actin serving as an internal reference; (C) Quantification of data in (B). All data are shown as the mean ± SEM of three independent experiments, and significant values are indicated with asterisks (*
p < 0.05; **
p < 0.01, versus scramble).