Ptger4 is a delayed-early gene that inhibits B cell proliferation. (A) Mouse splenic B cells stimulated with (BCR) or without (ctrl) anti-IgM F(ab′)2 for 72 h in culture. (B) BCR-induced expression of Ptger4 in mouse and human B cells as measured by qPCR at the indicated times. The relative abundances of each Ptger mRNA compared with Hprt transcripts in primary mouse B cells at time 0 h were as follows: Ptger4 (0.0068; 100%), Ptger2 (0.0013; 19.1%), Ptger1 (0.0009; 13.2%), and Ptger3 (2.2 × 10−6; 0.0003%). Western blotting (C) and immunofluorescence (D; at 48 h) of EP4 in BCR-stimulated mouse B cells. See Fig. S1 for higher protein loading and longer exposure immunoblot analysis, and Fig. S6 for higher quality immunofluorescence images. (E) Numbers of B cells isolated from spleen of Ptger4+/+ and Ptger4−/− mice. (F) ATP content of unstimulated and (H) BCR-stimulated mouse B cells in culture. (G) Cell cycle analysis at 60 h after BCR-triggering of mouse B cells of the indicated genotypes. Error bars are the SD of six to eight independent experiments. Bars, (A) 200 μm; (D) 100 μm. Figs. S1 and S2 are available.
