the cdp-choline pathway, first identified by eugene kennedy in 1956, is the predominant mechanism by which mammalian cells synthesize phosphatidylcholine (pc) for incorporation into membranes or lipid-derived signalling molecules. the cdp-choline pathway represents one half of what is known as the kennedy pathway. the other half is the cdp-ethanolamine pathway which is responsible for the biosynthesis of the phospholipid product phosphatidylethanolamine (pe).