PDGFRA and neoplasm: The tumor cells with the lowest degree of atypia, usually at the site of origin of the tumor, were not associated with overexpression of PDGFRA. Conversely, cells with the most atypia and aberrancy were found to have over-amplification of PDGFRA, suggesting PDGFRA is needed for tumorigenesis and the biopsy site is crucial for molecular studies [7].