Involved in angiogenesis; promotes angiogenic sprouting. May have potent implications in lung endothelial cell-leukocyte interactions. Monomer. Expressed in lung, on the vascular capillary network within alveolar walls, and also at lower level in kidney. By TNF and IL1B/interleukin-1 beta, but not IL4/interleukin-4. May contain intrachain disulfide bonds. O-glycosylated; contains chondroitin sulfate and dermatan sulfate.