Mutation of PDGF receptors in malignancies. PDGFRα (left part) has been found to be activated by point mutations in about 5% of GIST cases. In the figure a mutation is indicated (star) in the juxtamembrane domain, but can occur also in other parts of the protein. In HES the intracellular part of PDGFRα (red) has been found to be fused to FIP1L1 (green), and in CMML the intracellular part of PDGFRβ (blue) has been found to be fused to TEL (yellow). Other fusion partners have also been identified.