Figure 4.

Selective agonist for EP2, a PGE₂ receptor up-regulated during division, promotes heightened p53 mRNA. A) EP2 receptor expression is preferentially elevated with replicating B lymphoblasts in cultures activated by BCR:CD21-L, IL-4, and BAFF. Expression of each of 4 PGE₂ receptors on B cells was assessed with receptor-specific Abs, as described elsewhere (35). EP receptor density expressed as PE fluorescence; division number revealed by CFSE fluorescence. B) p53 mRNA-up-regulating effects of an EP2 receptor-specific agonist, butaprost. Levels of p53 mRNA in activated cultures exposed on d 4 to butaprost (or ethanol vehicle) were assessed at varying intervals after the pulse. qPCR fold Δ values from experiments with a common harvest interval following the pulse were pooled and expressed as means ± se. P values indicate that the level of p53 mRNA in butaprost-pulsed cultures is significantly different from that in control-pulsed cultures. C) Dose response of the p53 mRNA-up-regulating effects of butaprost (single experiment with all doses tested).