Figure 1
From: Myc stimulates cell cycle progression through the activation of Cdk1 and phosphorylation of p27
Myc-mediated induction of p27 phosphorylation in leukemia cells. (a) Kp27MER cells were treated with 50 µM Zn2+ and 200 nM 4HT for 24 hours as indicated to induce ectopic p27 expression and Myc-ER activation. Myc, Myc-ER, cyclins A2, B1 and E, Cdk1, Cdk2 and p27 levels are shown. Actin levels were used as loading control. (b) Immunoprecipitated Cdk2 (upper panel) and Cdk1 (lower panel) complexes from Kp27MER cells treated with Zn2+ and 4HT for 12 hours as indicated and subjected to in vitro kinase assays with His-p27 as substrate. Levels of Cdk1 and Cdk2 in immunoprecipitates are also shown. (c) Immunoprecipitated cyclin B1, cyclin A2, cyclin E complexes from Kp27MER treated with Zn2+ and 4HT for 12 hours as indicated and subjected to in vitro kinase assays using His-p27 as substrate. Levels of Cdk1 and Cdk2 present in cyclin A2, cyclin B1 and cyclin E are also shown. Asterix (*) in kinase assays shows light chain of the antibody from immunoprecipitation Signal densitometry quantification of the kinase assays are shown below each lane. Kinase buffer with His-p27 was used as negative control (No IP).
