Fatty Acids -- Transcriptional Regulation of Hepatic Fatty Acid Metabolism -- Modulation of Protein Function by Isoketals and Levuglandins -- Signalling Pathways Controlling Fatty Acid Desaturation -- Fatty Acid Amide Hydrolase: A Gate-Keeper of the Endocannabinoid System -- Modulation of Inflammatory Cytokines by Omega-3 Fatty Acids -- Eicosanoids in Tumor Progression and Metastasis -- Fatty Acid Synthase Activity in Tumor Cells -- Phospholipids -- Lipids in the Assembly of Membrane Proteins and Organization of Protein Supercomplexes: Implications for Lipid-linked Disorders -- Altered Lipid Metabolism in Brain Injury and Disorders -- Lysophospholipid Activation of G Protein-Coupled Receptors -- Phospholipid-Mediated Signaling and Heart Disease -- The Role of Phospholipid Oxidation Products in Inflammatory and Autoimmune Diseases -- Mediation of Apoptosis by Oxidized Phospholipids -- Sphingolipids -- Regulation of lipid metabolism by sphingolipids -- Multiple Roles for Sphingolipids in Steroid Hormone Biosynthesis -- Roles of Bioactive Sphingolipids in Cancer Biology and Therapeutics -- Glycosphingolipid Disorders of the Brain -- Role of Neutral Sphingomyelinases in Aging and Inflammation -- Sphingolipid Metabolizing Enzymes as Novel Therapeutic Targets -- Ceramide-Enriched Membrane Domains in Infectious Biology and Development -- Lipidomics -- MALDI-TOF MS Analysis of Lipids from Cells, Tissues and Body Fluids -- Lipidomics in diagnosis of lipidoses. Lipids are functionally versatile molecules. They have evolved from relatively simple hydrocarbons that serve as depot storages of metabolites and barriers to the permeation of solutes into complex compounds that perform a variety of signalling functions in higher organisms. This volume is devoted to the polar lipids and their constituents. We have omitted the neutral lipids like fats and oils because their function is generally to act as deposits of metabolizable substrates. The sterols are also outside the scope of the present volume and the reader is referred to volume 28 of this series which is the subject of cholesterol. The polar lipids are comprised of fatty acids attached to either glycerol or sphingosine. The fatty acids themselves constitute an important reservoir of substrates for conversion into families of signalling and modulating molecules including the eicosanoids amongst which are the prostaglandins, thromboxanes and leucotrienes. The way fatty acid metabolism is regulated in the liver and how fatty acids are desaturated are subjects considered in the first part of this volume. This section also deals with the modulation of protein function and inflammation by unsaturated fatty acids and their derivatives. New insights into the role of fatty acid synthesis and eicosenoid function in tumour progression and metastasis are presented.