For example, peptides containing Ans-Gly-Arg (NGR), Arg-Gly-Asp (RGD), or isoAsp-Gly-Arg (isoDGR) sequences selective for CD13 or integrins overexpressed by the tumor vasculature have been exploited as ligands for delivering tumor necrosis factor-α (TNF) [7], interferon (IFN) α2a [8], or IFNγ [9] to tumors, consequently improving their therapeutic index [7, 10]. The gene discussed is TNF; the disease is neoplasm.