For example, imatinib (Gleevec) is used to treat chronic myeloid leukemia [27] to block the BCR-ABL fusion kinase and gastrointestinal stromal tumors [28] to block hyperactive, mutant KIT, Gefitinib is used to treat non-small cell lung cancer patients with tumors exhibiting mutant EGFR [29], and Vemurafenib to treat melanoma because it is a potent inhibitor of hyperactive, mutant BRAF [30]. This evidence concerns the gene KIT and chronic myelogenous leukemia, BCR-ABL1 positive.