Figure 4(a) indicated that 786O and Caki-1 cells (invasive ccRCC cell lines) had a higher NNMT and MMP-2 expression than those of 769P and Caki-2 cells (primary ccRCC cell lines). The results of siRNA treatment showed that the knockdown of NNMT expression resulted in the suppression of MMP-2 expression in 786O and Caki-1 cells (Figure 4(b)). Here, MMP2 is linked to nonpapillary renal cell carcinoma.