the nck (non-catalytic region of tyrosine kinase adaptor protein 1) belongs to the adaptor family of proteins. the nck gene was initially isolated from a human melanoma cdna library using a monoclonal antibody produced against the human melanoma-associated antigen. the nck family has two known members in human cells (nck-1/nckalpha and nck2/nckbeta), two in mouse cells (mnckalpha and mnckbeta/grb4) and one in drosophila (dock means dreadlocks-ortholog).