PDGFRA and neoplasm: Approximately 85–90% of GISTs harbour activating mutations for the stem cell factor (SCF) receptor CD117 (c-Kit) or the alpha-type platelet-derived growth factor receptor (PDGFRα) (Heinrich et al, 2000; Hirota et al, 2000), which makes this tumour responsive to the tyrosine kinase inhibitor imatinib mesylate (Demetri et al, 2002).