For tumor subtype category (PCM and MM), this approach allowed us to identify a degree of correlation between the expression levels of genes involved in a) cell communication (KRT4, VWF and COMP); b) epidermal development (KLK7, LAMA3 and EVPL); and c) functionally related to kallikreins (EVPL, KLK6, KLK7, KLK8, SERPINB13, SERPING1 and SLPI). The gene discussed is KLK4; the disease is neoplasm.