Δ122p53 modulates p53 transactivation similar to Δ133p53. To demonstrate inhibition of p53-induced transcription by the Δ122p53 isoform, NIH3T3 cells were transduced with retrovirus vectors expressing Δ122p53 and Δ133p53. Vector-only control cells and Δ122p53- and Δ133p53-expressing cells were exposed to 50 J/m2 ultraviolet. (A) RNA was extracted after 10 hours, and quantitative RT-PCR was carried out for the p21 and Mdm2 genes. (B) Proteins were extracted after 6 hours, and p21 expression was determined by Western blotting. Experiments were repeated 3 times.