PECAM1 and lung carcinoma: In an analysis of the spatial localization of endothelial cells (CD31+) and pericytes (SMA+) during angiogenesis in spontaneous tumors of the pancreatic islet as well as in transplanted mammary and lung carcinomas, Morikawa et al found that, similar to our data, there was SMA-positive pericytic coverage or ‘sleeves’ at the leading edges of vascular sprouts [41].