PDCD4 and nonpapillary renal cell carcinoma: For example, circ-TNPO3 hindered ccRCC metastasis by binding to IGF2BP2 [17]; circular RNA ITCH suppressed ccRCC metastasis by regulating miR-106b-5p/PDCD4 axis [18]; circ-AKT3 inhibited ccRCC metastasis through changing miR-296-3p/E-cadherin signals [19].