FIGURE 3.

Elk1 increases DR5 transactivation (A and B), cooperates with CHOP to increase DR5 transcription and DR5 expression (C), mediates the effect of celecoxib on DR5 induction (D), and enhances celecoxib-induced DR5 expression (E). A and B, HEK293T cells were co-transfected with the given DR5 promoter reporter and Elk1 expression plasmids for 36 h. C, HEK293T cells were co-transfected with the given DR5 promoter reporter plasmid with empty pcDNA, Elk1, CHOP, or CHOP plus Elk1 expression constructs for 40 h. After the aforementioned transfections, the cells were harvested for luciferase assay and Western blot analysis. D, the given cell lines were transfected with control (Ctrl) or Elk1 siRNA for 40 h and then treated with and without 50 μm celecoxib (CCB) for an additional 10 h. E, H1299 cells were transfected with the indicated plasmids for 36 h and then treated with and without 50 μm celecoxib for an additional 10 h. After treatment, the cells were harvested for preparation of whole cell protein lysates and subsequent Western blot analysis.