Blue type = enzyme. (a) The 3 dominant pathways leading to the production of PC. LysoPCs can be used to make PC or LPA. The effect of decreased lysoPC and production of LPA are typed in red. (b) The carnitine shuttle is used to transport long chain FAs into the mitochondria to undergo β-oxidation which ultimately leads to the final oxidation product (in red), acetyl-CoA. (c) Pathway for the metabolism of SMs (and vice versa) to S1P, an important regulator in the liver for fibrosis. CK, choline kinase; CT, Cytidine; CDP-choline, cytidine-5′-diphosphocholine; CPT, CDP-choline:1,2-diacylglycerol cholinephosphotransferase; PEMT, phosphatidylethanolamine N-methyltransferase; PLA2, phospholipase-α2; LCAT, lecithin-cholesterol acyltransferase; LPCAT, lysophosphatidylcholine acyltransferase; LPA, lysophosphatidic acid; PC, phospatidylcholine; PE, phosphotidylethanolamine; LysoPC, lysophosphatidylcholine; TNF-α, tumor necrosis factor-α; IL-1β, interleukin-1β; SCD1, stearoyl-CoA desaturase 1; CPT1,2, carnitine palmitoyltransferase 1,2; CACT, carnitine-acylcarnitine translocase; LCAcylCoA dehydrogenase, long chain acyl-CoA dehydrogenase; NSMase, neutral sphingomyelinase; ASMase, acidic sphingomyelinase; SM synthase, sphingomyelin synthase; S1P, sphingosine-1-phosphate.