To prove that the effects we have described were caused by interactions of the HLA-B,C-specific mAb B1.23.2 with the gene products of the HLA-B and C loci and not with unrelated molecules, we tested whether the HLA-B,C-specific mAb B1.23.2 had any effects on the metabolism of FO-1 melanoma cells. The gene discussed is HLA-B; the disease is melanoma.