The invention provides high affinity antibodies suitable for forming immunotoxins that inhibit the growth of cells expressing human glycoprotein NMB, including glioblastoma multiforme cells, anaplastic astrocytoma cells, anaplastic oligodendroglioma cells, oligodendroglioma cells, and melanoma cells. The antibodies may be formed in cells transformed with an isolated nucleic acid encoding a polypeptide comprising an antibody heavy chain variable region (“VH”) and an antibody light chain variable region (“VL”). Such nucleic acids are provided.
