The DAN (differential screening-selected gene aberrative in neuroblastoma) protein family contains antagonists of bone morphogenetic protein (BMP) signaling that are expressed in the neural crest. All family members are secreted proteins that act as BMP antagonists in embryonic explants and are expressed in the proximal airway epithelium of the lung during embryonic development. This family includes the head-inducing factor Cerberus, the dorsaling factor gremlin and the tumor suppressor DAN. DAN, also known as zinc finger protein DAN, NO3, DAND1 or neuroblastoma suppressor of tumorigenicity 1 (NBL1), is a secreted protein containing one C-terminal cysteine knot-like (CTCK) domain. It is produced in small neurons of the dorsal root ganglion and its expression is activated by MATH-1. In addition to antagonizing BMP signaling, DAN also antagonizes the action of TGF(beta). DAN is a possible tumor suppressor for human neuroblastoma; defects may result in or contribute to its progression. DAN may also be a neuromodulator in inflammatory pain.