CD38 is a 42 kD type II transmembrane glycoprotein that uses nicotinamide adenine dinucleotide (NAD) as a substrate to form cyclic adenosine diphosphate ribose (cADPR). This novel multifunctional ectoenzyme has both cyclase and hydrolase enzymatic activity, and is expressed on the surface of most white blood cells (CD4+, CD8+, B-lymphocytes and natural killer (NK) cells). It is also expressed at high levels in normal tissues and organs like the pancreas, liver, and kidney as well as in malignant lymphoma and neuroblastoma.
