PECAM1 and neoplasm: CD31 has been considered an ideal biomarker for vascular endothelial cells and its density is generally represented by the tumour MVD.26, 30 The results indicated that TIPE2 overexpression reduced the expression of CD31, while TIPE2 knockdown promoted the expression of CD31 in rectal adenocarcinoma xenograft tumours, suggesting that TIPE2 could regulate the growth of human rectal adenocarcinoma xenograft tumours by mediating angiogenesis.