Apelin is among the most potent stimulators of cardiac contractility known. The apelin-APJ signaling pathway is an important novel mediator of cardiovascular control. Apelin is an adipokine secreted by adipocytes where it is co-expressed with apelin receptor (APJ) in adipocytes. It suppresses adipogenesis through MAPK kinase/ERK dependent pathways and prevents lipid droplet fragmentation, thereby inhibiting basal lipolysis through AMP kinase dependent enhancement of perilipin expression. It also inhibits hormone-stimulated acute lipolysis through decreasing perilipin phosphorylation. Apelin induces a decrease of free fatty acid release via its dual inhibition on adipogenesis and lipolysis. As a vaso-active and vascular cell growth-regulating peptide Apelin is a target of the BMP pathway, the TGF-beta/bone morphogenic protein (BMP) system - a major pathway for angiogenesis.