Moreover, unlike the frequent downregulation of major histocompatibility complex (MHC) class I and II genes essential for antigen presentation and activation of the adaptive immune system in ECs evident in malignant tumour tissues,62, 63 MHC class I genes such as human leukocyte antigen A (HLA‐A), HLA‐B and HLA‐C and MHC class II genes such as HLA‐DRA, HLA‐DPA1 and HLA‐DQB1 were expressed at comparable levels in PA and PG ECs (Figure 5F). This evidence concerns the gene HLA-C and cancer.