(a) Selected enzymatic pathways that generate FA in biological systems. (b) Subcellular localization of FA-generating enzymes. Abbreviations: α-KG, α-ketoglutarate; KDM, lysine demethylase; ALKBH, AlkB homologues; SSAO, semicarbazide-sensitive amine oxidases; DMGDH, dimethylglycine dehydrogenase; SARDH, sarcosine dehydrogenase; FTO, fat mass and obesity-associated protein.