A mixture of phosphatidic acids isolated from chicken egg; a phospholipid and an intermediate in glycerolipid biosynthesis; has a role in shaping cellular membranes, cellular signaling, vesicle fission and fusion, as well as mitochondrial division and fusion; stimulates respiratory burst in neutrophils independent of diacylglycerol and activates monoacylglycerol acyltransferase, PLC, Ras, and PIP4 kinase in several cell lines