- The p53 gene product suppresses both tumor cell growth and the cellular transformation process promoted by oncogenes. Although several genes are known to be positively regulated by p53, it is unclear how many gene expression events are involved in p53-mediated growth arrest and apoptosis. Two-dimensional gel electrophoresis was employed to investigate changes in whole-cell protein expression in p53-null H1299 cells that were transfected with a recombinant adenovirus expressing wild-type p53 at high efficiency. The two-dimensional gel analysis was restricted to proteins ranging in mass from 12,000 to 80,000 daltons. A total of 17 proteins were induced and one was repressed within 16 h of expression of exogenous wild-type p53 in H1299 cells. These results indicate that p53-mediated growth suppression involves a complex array of gene expression events.