KRT5 and neoplasm: We found Ck5-positive tumour cells, glandular (Ck8/18+) and myoepithelial cells (SMA+), as well as cells co-expressing Ck5 and one of the lineage differentiation markers (either Ck5+, Ck8/18+ or Ck5+, SMA+) in all of these lesions (Fig 1, G, H).