MMP9 and nonpapillary renal cell carcinoma: In addition, we analyzed the RNA-seq data of 533 ccRCC patients from TCGA and found that SALL4 mRNA level was significantly correlated with the transcripts of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) related to tissue remodeling and tumor invasiveness [22, 23], including MMP9 (r = 0.1227, P = 0.0005), MMP25 (r = 0.2601, P < 0.0001), TIMP3 (r = − 0.2221, P < 0.0001) and TIMP4 (r = − 0.2761, P < 0.0001) (Fig. 3e-h and Additional file 6: Figure S5, Additional file 7: Table S2).