PTGER4 and adenoma: Deletion of myeloid cell EP4 receptors markedly reduced adenoma number and size (adenoma/mouse: 27.3 ± 4.1 vs. 83.6 ± 7.0 of WT ApcMin/+ mice, P < 0.0001, n = 15 in WT ApcMin/+ mice and n = 14 in myeloid EP4−/−ApcMin/+ mice) (Figure 2A).