FIG. 3.

(A) VRK1 increases the stability of p53 by a posttranslational mechanism. H1299 cells were transfected with p53 with (+) and without VRK1. Twenty-four hours after the transfection, cycloheximide (CHX) was added to the cultures and the levels of p53 protein at different time points were determined by Western blotting. The quantitation of protein levels is shown below the blot. The half-life of p53 increased from 8 to 13.5 h in the presence of VRK1. The straight lines represent the linear regression adjustment of the individual time points. (B) VRK1 overexpression does not affect p53 RNA levels. Real-time quantitative RT-PCR was performed with 100 ng of total RNA obtained from H1299 cells transfected as for Fig. 2A. The amplification curve and a sample of the final product in an agarose gel (inset) are shown.