FIG. 6.
(A and B) p38α and PU.1 work in the same pathway to regulate the IL-3 inducibility of SIE-containing reporters. (A) Ba/F3 cells transfected with the p(−203/+10)mcl-luc reporter along with a control vector or vectors expressing DN-PU.1, DN-p38α, and DN-p85 or a combination of these expression vectors were left untreated or stimulated with IL-3 for 12 h before cell lysates were prepared and analyzed for luciferase activity. The data shown here are representative results of three to five independent experiments performed in duplicate. Luciferase activity was plotted as described in legend to Fig. 3. The differences between the results shown in lanes 3 and 6 and between those shown in lanes 4 and 7 are statistically significant. (*, P = 0.0001; **, P = 0.003). (B) Same conditions as in lanes 1 to 4 and 8 of panel A, except that the pGL-8XSIE reporter was used in the assay. (C) The p38MAPK pathway is involved in the viability response of IL-3 in Ba/F3 cells. Ba/F3 cells cultivated in growth medium containing IL-3 were treated with various chemical inhibitors as indicated. Fifteen hours after each treatment, cells were harvested and the percentage of apoptotic cells in each group was quantified by flow cytometric analysis of cells with a sub-G1 DNA content. The data shown are representative results of two independent experiments performed in duplicate. DMSO, dimethyl sulfoxide.