Normally, the targeting is achieved by deleting the cell receptor-binding R-domain and combining the remaining portion (containing T- and C-domains) with proteins that selectively bind to the surface of cancer cells (one such fusion protein, which contains human interleukin-2 and truncated diphtheria toxin, is approved for use in cutaneous T-cell lymphoma [54,59,60]). The gene discussed is IL2; the disease is cancer.