To investigate the effect of CD73 on apoptosis in PTC, tumor cells were transfected with CD73-siRNA or treated with APCP, and then the percentage of apoptotic cells was analyzed by R-phycoerythrin-conjugated annexin V (PE) and propidium iodide (PI) double staining and fluorescence-activated cell sorting (FACS). The gene discussed is NT5E; the disease is neoplasm.