Fig. 4.
Effects of ATI on cell cycle progression and cell cycle modulators. (A) ATI treatment leads to the G1/G0 arrest of NB4 and NB4-R2 cells. (B) Effects of the ATI combination on important cell cycle regulators in NB4 (Left) and NB4-R2 (Right) cells. (C) Down-regulation of CDK2 by ATI treatment on NB4 (Upper) and NB4-R2 (Lower) cells results in decrease of phosphorylated H1. Cells are treated with A, T, I, and the combined drugs for 24 h. CDK2 is immunoprecipitated (IP) from cell lysates and assayed for kinase activity using Histone H1 as a substrate. The efficiency of IP is confirmed and quantitated by Western blot analysis, and CDK2 at each treatment group is adjusted to the same level.