Human epidermal growth factor receptor 2 (HER2) and fibroblast growth factor-inducible 14-kDa protein (Fn14) are frequently co-expressed in human breast tumors, and HER2 directly induces an increase in Fn14 expression, making tumor cells sensitive to an immunotoxin made by fusing Fn14 antibodies to recombinant gelonin (designated hSGZ) (64). This evidence concerns the gene TNFRSF12A and neoplasm.