KRT5 and squamous cell carcinoma: Bas tumors, formerly labeled as the TCGA cluster III/IV, the Lund “urothelial-like B” subtype, and the Lund “squamous cell carcinoma-like” subtype [38], show high levels of genes associated with cells present in the basal layer within normal urothelium or stem cells, resulting in their staining with basal urothelial stem cell markers (e.g., EGFR, CD44, CK5 and/or CK5/6, and CK14), while lacking markers of urothelial differentiation (e.g., luminal transcription factors GATA3 and FOXA1, and CK20) [7,8,38,39,40].