Myc activation induces rapid loss of Paneth but not enteroendocrine cells. (A to D) Paneth cells, identified by immunofluorescence staining for lysozyme (in green; Hoechst counterstain in red), disappeared rapidly but sporadically during 3 days of Myc activation. (E to H) Enteroendocrine cells, identified by anti-5-HT immunostaining, were largely unaffected by Myc activation (5-HT staining in green, Hoechst counterstaining in red). tam, tamoxifen.