FIG. 1.

Loss of the S-phase entry-promoting function in a human cyclin A mutant (CycA-C1). (a, b, and c) NIH 3T3 cells were cotransfected with 1 μg of GFP-expressing vector and 5 μg each of mock, myc-tagged (MT) wild-type (WT) or mutant (C1) cyclin A (cycA)-expressing vector and subjected to FACS analysis of the GFP-positive cells (a) and anti-cyclin A Western blot analysis (b); 1, 2, and 4 μg of the cyclin A-expressing vectors were used for anti-myc tag immunoprecipitation/histone H1 kinase assays (c). (d) NIH 3T3 cells were cotransfected with 1 μg of GFP-expressing vector and 5 μg of either mock, MTcycA-WT-expressing, or MTcycA-WT vector plus 2 μg each of wild-type or dominant negative CDK2-expressing vector and subjected to FACS analysis of the GFP-positive cells. The transfection control contained the CDK2-dn vector without cyclin A.