FIG. 5.

Activation of E2F1 results in increased expression of NPAT. (A) E2F1 up-regulates NPAT mRNA expression. ER-E2F1-expressing WI38 cells were treated with OHT and cycloheximide (CHX) or not treated for 4 h as indicated. mRNA was isolated and analyzed by Northern blotting. As previously reported (17), two NPAT mRNA bands were detected in human cells. As a positive control, the cyclin E1 (CCNE1) mRNA in the same samples was also analyzed. EtBr, ethidium bromide staining of the 28S RNA, used as a loading control. (B) Western blot analysis of NPAT protein in ER-E2F1-expressing cells following OHT treatment. The NPAT protein was detected by using a mouse monoclonal anti-NPAT antibody (56). The analysis of the actin protein, serving as a loading control, is also shown.