Supplementary Figure 1.

Representative IHC for lineage-identifying antibodies. (A) Set 1: H⁺K⁺ATPase (DAB-brown) and pepsinogen (AP-blue). (B) Set 2: MUC5AC (DAB-brown) and MUC2 (AP-blue). (C) Set 3: HD6 (AP-blue). Additionally, we show that distinct gland types are evident through double IHC. (D) An FFPE biopsy specimen that shows both squamous and Barrett’s epithelium stained with H&E and (E) a serial section stained with MUC2 and MUC5AC. Three areas are highlighted in higher power (Di–iii, Ei–iii). Area 1 shows MUC2⁺ with light MUC5AC⁺ cells within the same specialized gland (∗) and a MUC2⁺MUC5AC^– (§) mature intestinal gland. In areas 2 and 3 (Dii and iii, Eii and iii) MUC2⁺ cells are completely absent. The IHC clearly defines specialized and cardiac-type epithelium as well as a likely mature intestinal gland. (HD6 staining is not present to confirm the presence of Paneth cells.)