Phospholipase A2 -PLA2) catalyzes the hydrolysis of phospholipids at the sn-2 position yielding a free fatty acid and a lysophospholipid. The release of arachidonic acid from the membrane phospholipids by PLA2 is believed to be a key step in the control of eicosanoid production within the cell. Human synovial sPLA2 is a secreted 14 kDa protein which is dependent on Ca2+ for optimal activity. Human synovial sPLA2 is 79% homologous to rat platelet and murine type II sPLA2s.