The development of TKIs for ErbB family tyrosine kinase receptors has led to the use of several FDA-approved anti-cancer drugs such as gefitinib (Iressa, ZD1839), erlotinib (Tarceva, CP-358774, OSI-774), lapatinib (GW-572016), trastuzumab (Herceptin), and cetuximab (Erbitux) [45–48]. The gene discussed is NTRK1; the disease is cancer.