CD109 is a glycosylphosphatidylinositol-linked glycoprotein that belongs to the α2-macroglobulin (α2M)/C3, C4 and C5 complement superfamily.1 Upregulation of CD109 was found in pancreatic cancer,2 hepatocellular carcinoma,3 malignant melanoma4 as well as in squamous cell carcinomas of the uterine cervix,5 lung,6,7 oesophagus,6,8 stomach,6 oral cavity,9 gallbladder,10 penis11 and skin,12 which suggested that CD109 might be a cancer-associated marker in various carcinoma models. The gene discussed is CD109; the disease is carcinoma.