FIG. 5.

(A) K-bZIP slows down cell cycle division. A total of 5 × 10⁴ K-bZIP-BCBL-1 cells or parental BCBL-1 cells were seeded in 60-mm plates and cultured in 15% fetal bovine serum-RPMI 1640. Cell numbers were counted at the indicated time points. Triplicate plates were seeded for each cell clone. (B) Inhibition of CDK2 kinase activity in K-bZIP-BCBL-1 cells. CDK2 kinase activity was determined by the in vitro kinase assay after induction of K-bZIP expression (72 h). CDK2 was immunoprecipitated from K-bZIP-BCBL-1 or parental BCBL-1 cells. Histone 1 was used as a substrate for the assay. The amounts of CDK2 were measured by immunoblotting. W.B, Western blotting.