Myeloma. Animals were immunized with a transfected NIH 3T3 cell line, 18-3-7, that expresses full length normal human neu protein. Spleen cells were fused with SP2/O myeloma cells. The antibody recognizes substantially purified p100, human neu related protein, the full-length HER-2/neu molecule in tumor tissue (p185) or the extracellular domain (ECD) (p105) in serum, plasma, cell cultures and fluids.