The mean mRNA expression levels of these genes were not significantly different between the 523 ccRCC and 100 normal tissues (P > 0.05; Fig. 2); however, both PIK3CD and PIK3CG displayed an upward trend while mTOR displayed a decreasing trend, but not significant expression levels in patients with ccRCC (P > 0.05). This evidence concerns the gene PIK3CD and nonpapillary renal cell carcinoma.