PDGFRB and gastrointestinal stromal tumor: Further studies demonstrated that Imatinib, beside BCR-ABL, is also able to inhibit platelet-derived growth factor receptor (PDGFR) and mast/stem cell growth factor receptor (SCFR), also known as proto-oncogene c-Kit, frequently mutated in gastrointestinal stromal tumor (GIST) (Buchdunger et al., 2000; Tuveson et al., 2001).