Immunofluorescent staining of HNF4α in the gastric epithelium. Images of HNF4α (green) expression in the nucleus (blue) of isthmal progenitor and pit cells (white arrowheads), neck cells (red arrowheads, GSII = purple), and zymogenic cells (pink arrowheads, GIF = red), but again not in parietal cells (yellow arrowheads). Top panel: HNF4α and nuclei; bottom panel: merge with all 4 colors. B: immunohistochemical stain for HNF4α (brown) in region of gastric pit shows strong pit cell nuclear staining (white arrowheads) and only background staining in parietal cells (yellow arrowheads). Scale bars represent 20 μm.