Fig. 5. CDX2 expression analysis in esophageal cells grown on filters and in cell lysates. (A) Caco2 cells, used as control, were all CDX2 positive. (B) Esophageal cells at D+18 grown at pH 7.4 exhibited no CDX2 staining, whereas (C) positive nuclear staining was observed in some cells grown at pH 3.5. Scale bar, 20 µm. (D) Western blot analysis of CDX2 protein expression performed on lysates of cells at D+18 at pH 7.4 (lane 2), pH 5 (lane 3), and pH 3.5 (line 4). Lane 1 represents the positive control for Cdx2 protein in Caco2 cell lysate (C+).