Apart from these potential markers, activating mutations of KIT and, less commonly, of PDGFRα–which encode the stem-cell factor receptor (KIT) and platelet-derived growth factor receptor α (PDGFRα) tyrosine kinases, respectively–are believed to be critical in tumorigenesis in GIST 14,15. The gene discussed is PDGFRA; the disease is gastrointestinal stromal tumor.