As shown in Figure 4 and Supplementary Table S1, the mRNA expressions of enzymes nicotinamide riboside kinase 2, aldehyde oxidase 1 (NT5C1B) and quinolinate phosphoribosyltransferase were up-regulated, whereas ADP-ribosyl cyclase 1 (CD38) was down-regulated in opioid-exposed ccRCC specimens. Here, NMRK2 is linked to nonpapillary renal cell carcinoma.