Then, the result of qRT-PCR experiment which was conducted using 30 local hospital ccRCC and paired normal renal tissues also supported the aberrant gain of expression of all four genes including MMP9, IRF7, NFKB1 and HMOX1 in ccRCC (Fig. 4C, F, I, L). Here, MMP9 is linked to nonpapillary renal cell carcinoma.