Furthermore, both ASS1 and ASL mRNAs are consistently underexpressed in ccRCC tumors when compared to normal kidney tissues (Fig. 1D), especially ASS1. This is also reflected in the lowered protein abundances of ASS1 and ASL in 50 matched primary patient tumor-normal cores (Fig. 1E and Supp Figure 1 C). This evidence concerns the gene ASL and nonpapillary renal cell carcinoma.