PDGFRA and gastrointestinal stromal tumor: Our data suggest that loss of miR-34a may be an alternative event leading to the activation of PDGFRA in GIST cells, and that replacement of miR-34a could potentially exert a therapeutic effect through downregulation of PDGFRA. We observed that PDGFRA knockdown in GIST-T1 cells suppressed cell viability, though the effect was relatively limited, as compared to that of miR-34a.