Fig. 6.
Effect of 6,7,4′-THIF on CDK1 or CDK2 activity in vivo. (A) 6,7,4′-THIF inhibits CDK1 and CDK2 activity in tumor extracts. Data are shown as means ± standard deviations of the 32P count from three mice in each group from three separate experiments. The asterisk (*) indicates a significant difference (P < 0.05) between groups treated with 6,7,4′-THIF and untreated control groups. (B) 6,7,4′-THIF directly interacts with CDK1 and CDK2 in tumors. CDK1– and CDK2–6,7,4′-THIF binding was confirmed by immunoblotting using an antibody against CDK1 (left panel) or CDK2 (right panel): lane 1 (input control), whole tumor lysates from nude mice; lane 2 (control), whole tumor lysates from nude mice precipitated with Sepharose 4B beads and lane 3, whole tumor lysates from nude mice precipitated by 6,7,4′-THIF–Sepharose 4B beads.