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 (By similarity). 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 (in vitro) (By similarity). Depending on context, may modulate tumor-related angiogenesis (By similarity). Mediates inactivation of the lipoprotein lipase LPL, and thereby plays an important role in the regulation of triglyceride clearance from the blood serum and in lipid metabolism. Has higher activity in LPL inactivation than the uncleaved protein. Homooligomer; disulfide-linked via Cys residues in the N-terminal part of the protein. The homooligomer undergoes proteolytic processing to release its carboxyl fibrinogen-like domain, which circulates as a monomer (PubMed:14570927). The homooligomer unprocessed form is able to interact with the extracellular matrix (By similarity). The unprocessed form interacts with the extracellular matrix. This may constitute a dynamic reservoir, a regulatory mechanism of the bioavailability of ANGPTL4. N-glycosylated. Forms disulfide-linked dimers and tetramers. Cleaved into a smaller N-terminal chain and a larger chain that contains the fibrinogen C-terminal domain; both cleaved and uncleaved forms are detected in the extracellular space. The cleaved form is not present within the cell.