(A) Bar plots showing significantly increased PLA2 activity in all the HNSCC cells compared to NHOK. ***P < 0.001. (B) Bar plots showing significantly increased cPLA2 activity in all the HNSCC cells compared to NHOK. **P < 0.01. (C) Schematic representation of biosynthesis and hydrolysis of PC in HNSCC effected by three major enzymes, phospholipase A1 and A2 (PLA1 and PLA2), phospholipase C (PLC) and phospholipase D (PLD). These phospholipases (indicated by red arrows) can be potential drug targets for head and neck cancer. Metabolites: CDP-Cho, cytidine 5`-diphosphocholine; Cho, choline; DAG, diacylglycerol; FFA, free fatty acid; G3P, sn-glycerol-3-phosphate; GPC, glycerophosphocholine; PA, phosphatidic acid; PCho, phosphocholine. Enzymes: ck, choline kinase; ct, cytidylyltransferase; lpl, lysophospholipase; pct, phosphocholine transferase; pd, glycerophosphocholine phosphodiesterase.