NGAL (neutrophil gelatinase-associated lipocalin) belongs to the lipocalin family of proteins. These are typically small secreted proteins characterized by their ability to bind small, hydrophobic molecules in a structurally conserved pocket formed by beta-pleated sheet, to bind to specific cell-surface receptors and to form macromolecular complexes. NGAL has many synonyms: it also known as NL (neutrophil lipocalin,HNL, rat NL), lipocalin, oncogene protein 24p3 or uterocalin (in the mouse) and neu-related lipocalin or 25 kDa alpha 2-microglobulin-related protein6 (in the rat). Rat NGAL consists of a single disulfide-bridged polypeptide chain of 178 amino-acid residues with a calculated molecular mass of 22 kDa, but glycosylation increases its apparent molecular mass to 25 kDa.