The best example of a successful RTK-inhibitor is imatinib that inhibits both c-KIT and platelet-derived growth factor receptor alpha (PDGFRα) and it is currently used for treating, amongst others, gastrointestinal stromal tumors (GISTs) and chronic myeloid leukemia (CML) [16]. The gene discussed is PDGFRA; the disease is gastrointestinal stromal tumor.