KLK4 and squamous cell carcinoma: A subset of the genes upregulated in the SqD regions were genes previously reported to be highly expressed in squamous carcinomas of various lineages, including the peptidase kallikrein genes KLK1326, KLK1027, and KLK1228, the cornification-related genes CNFN and PLA2G4E29, the small proline-rich protein genes SPRR2D and SPRR2E30, the keratin genes KRT1631, KRT3132and KRTDAP33, the interleukin IL36G34, and the desmogleins DSG1/3/4 and desmocollins DSC2/335,36(Fig. 3b).