FIGURE 5.

Translational suppression by Pdcd4 is mediated by the p53 5′-UTR and is dependent on the ability of Pdcd4 to interact with eIF4A. A, QT6 fibroblasts were transfected with increasing amounts of expression vector for human Pdcd4 and plasmids containing the luciferase coding region and the p53 5′-UTR. Cells were additionally transfected with the β-galactosidase expression vector pCMVβ to normalize the transfection efficiencies. The bars show the β-galactosidase-normalized luciferase activities of cell extracts prepared 24 h after transfection. B, cells were transfected and analyzed as described for A except that equal amounts of expression vector for WT human Pdcd4 or a Pdcd4 mutant not able to interact with eIF4A (Pdcd4-mut4) were transfected. Comparable expression of both Pdcd4 proteins was confirmed by the Western blot shown at the bottom.