KRT7 and Barrett esophagus: Instead, complete recombinants expressed several genes enriched at the SCJ of the GI tract, which contains a small but distinct non-keratinized transitional columnar epithelium marked by high levels of CK7 (Jiang et al., 2017). The transitional epithelium consists of a ΔNp63-positive basal progenitor layer, which can give rise to Barrett’s metaplasia, and a differentiated ΔNp63-negative luminal layer.