KRT5 and breast cancer: Using a combination of these markers, 60 HR+/HER2+ breast cancer patients were classified into the following subtypes: (a) IHC-III: CD8A+; (b) IHC-IV: CD8A− and KRT5+; (c) IHC-II: CD8A−, KRT5− and GFRA1+; (d) IHC-I: CD8A−, KRT5−, GFRA1− and PFKP+ (Fig. 6b).