RARRES1 and neoplasm: RARRES1 is a transmembrane carboxypeptidase inhibitor that interacts with the carboxypeptidase ATP/GTP-binding protein like 2 (AGBL2).6 Decrease or lack of RARRES1 expression, frequently caused by promoter hypermethylation, has been described in prostate, endometrial, head and neck, nasopharyngeal, colorectal and gastric cancer cell lines suggesting that RARRES1 is a tumour-suppressor gene.7–13 Studies carried out on human tumour tissues yielded controversial results.