Introduction 3. The extracellular domain 3.1. The conserved region 3.1. 1. The link module 3.1. 2. N-glycosylation sites 3.1. 3. Outside the link module 3.2 The non-conserved region 3.2. 1. Carbohydrate modifications 3.2. 2. Variable sequences 3.2. 3 Soluble CD44 4. The transmembrane domain 4.1 Insolubility in nonionic detergents 4.2 Palmitoylation and dimerization 5. The cytoplasmic domain 5.1. Regulation of ligand binding 5.2. Phosphorylation 5.3. Localization in the plasma membrane 5.4. Association with the cytoskeleton 5.4. 1. Association with ankyrin 5.4. 2. Association with microfilaments 5.5. Signal transduction 6. Perspectives 7. Acknowledgments 8. References