TGM2 and nonpapillary renal cell carcinoma: Although transglutaminase 2 (TGase 2) expression is reported to be high in ccRCC, and TGase 2 inhibition showed significant potential for a therapeutic approach for ccRCC in a series of past studies [19,20,21,22,23], the CPTAC study did not reveal any significance of TGase 2 in ccRCC [18].