Ligands such as Tumor Necrosis Factor-Related Apoptosis-Inducing Ligand (TRAIL) [265], Frizzled 10 (FZD10) Protein [266], EpCAM Aptamer [267], Programmed Cell Death Protein 1 (PD-1) [268], RGD [269], CC-9 and RH-20 [270], and specific DNA sequences [271] have demonstrated enhanced uptake by cancer cells and cytotoxicity. The gene discussed is PDCD1; the disease is cancer.