MAFP (Methyl Arachidonyl Fluorophosphonate) is an selective, active-site directed and irreversible inhibitor of cPLA2 and iPLA2. MAFP is also a potent irreversible inhibitor of anandamide amidase. IC50 & Target: cPLA2, iPLA2^[1], Anandamide amidase^[2] In Vitro: MAFP inhibits iPLA2, in a concentration-dependent manner with an IC₅₀ of 5 μM after a 5 min preincubation at 40°C in P388D1 cells. cPLA, is a phospholipid hydrolase using the hydroxyl of serine-228 residue as its catalytic nucleophile^[1]. MAFP is also an inhibitor of anandamide amidase and as a ligand for the CB1 cannabinoid receptor. MAFP demonstrates selectivity towards anandamide amidase for which it is approximately 3000 and 30000-fold more potent than it is towards chymotrypsin and trypsin, respectively. MAFP displaces [³H]CP-55940 binding to the CB1 cannabinoid receptor with an IC₅₀ of 20 nM vs 40 nM for anandamide^[2].