Research Paper Volume 1, Issue 9 pp 803—817

Figure 1. TTP inhibits HeLa cell proliferation through induction of senescence. (A) HeLa Tet-Off/TTP-Flag cells grown in the presence or absence of 2 μg/ml Dox for 48 hr. The expression of TTP-Flag was detected by western blot (WB) using antibodies against the Flag epitope (left panel) or TTP (right panel). Actin was used as a loading control. (B) Growth curves of HeLa Tet-Off/TTP-Flag (circles) and parental HeLa Tet-Off (triangles) cells in the presence (open symbols) or absence (filled symbols) of 2 μg/ml Dox. On day 4 of growth, Dox was added to HeLa Tet-Off/TTP-Flag cells to repress TTP expression. Each point represents the mean of 4 replicates. (C) HeLa Tet-Off/TTP-Flag cells were grown in the presence or absence of Dox to repress (- TTP) or induce (+ TTP) TTP, respectively. Phase contrast (top panels) and fluorescence (middle panels) microscopy of cells after 48 hr of TTP expression; original magnification 200X and 400X, respectively. Nuclei (blue) and cytoskeleton (red) are shown in fluorescent micrographs. HeLa-Tet-Off/TTP-Flag cells were stained for SA-β-gal activity (bottom panels) after 12 days of TTP expression.