PECAM1 and neoplasm: VM channels occur in at least 10 tumour types that are aggressive, highly metastatic and inclined to poor differentiation.6, 10, 13, 14 The term VM refers to the ability of aggressive tumour cells to form periodic acid‐Schiff‐positive and CD31‐negative cells that line VM networks in vivo and form tubular structures and patterned networks in three‐dimensional (3D) cultures in vitro.10, 12