Fig. 3. Immunostaining of COX-1, COX-2, and mPGES in serial sections of the rare small intestinal polyps in the compound mutants of Apc with the COX-1 or COX-2 gene. Expression of COX-2 (A) and mPGES (B) in the ApcMin COX-1 (−/−) mouse polyp. Expression of COX-1 (C) and mPGES (D) in the ApcΔ716 COX-2 (−/−) mouse polyp. Arrows indicate representative positively stained stromal cells in the same polyp subregion. Bars, 50 μm.