Mediates inactivation of the lipoprotein lipase LPL; and thereby plays a role in the regulation of triglyceride clearance from the blood serum and in lipid metabolism. May also play a role in regulating glucose homeostasis and insulin sensitivity. Inhibits proliferation; migration; and tubule formation of endothelial cells and reduces vascular leakage. Upon heterologous expression; inhibits the adhesion of endothelial cell to the extracellular matrix (ECM); and inhibits the reorganization of the actin cytoskeleton; formation of actin stress fibers and focal adhesions in endothelial cells that have adhered to ANGPTL4-containing ECM . Depending on context; may modulate tumor-related angiogenesis.