Immunoblot analysis of cyclin A, CDK2, and p27^Kip-1 proteins in DAA-3 cells.

The cells were cultured for 2 and 4 days in SFM (center) alone or supplemented with either 10⁻⁶ mol/L 13-cis-RA (RA), 10⁻⁶ mol/L Dex, or a combination of these 2 drugs. For CDK2, faster migrating bands represent the phosphorylated active forms of this kinase. Dex induced a decrease in the amount of p27^Kip-1 protein and a markedly contrasted p27^Kip-1 up-regulation induced by RA. Dex also increased the levels of the phosphorylated active forms of CDK2 and antagonized an RA-induced decrease of CDK2 phosphorylation. Similar findings were obtained with the HDE-14 LCLs (not shown). We subjected 50 μg extract proteins from each lysate to immunoblot analysis. The cellular proteins visualized in each panel are indicated to the left.