PECAM1 and pulmonary fibrosis: P2Y6 shows prominent expression within infiltrating T lymphocytes of inflammatory bowel disease (IBD) patients, breast cancer (BC) tissues and intestinal epithelial cells (34, 35), virus-infected macrophages (36), epithelial cells and fibroblasts during allergic inflammation and pulmonary fibrosis, together with CD31+ endothelial cells among atherosclerosis patients (37, 38).