PLK4 and nonpapillary renal cell carcinoma: The qPCR experiments showed that miRNA-has-miR-214-3p negatively regulated the expression of PLK4 (Figure 2(c)), while PLK4 was expressed at a higher level in ccRCC than in paracancerous tissues, suggesting that the high expression of PLK4 in ccRCC may be related to the low expression of miRNA-has-miR-214-3p in ccRCC.