The ACAT1 mRNA level was down-regulated 2.26-fold (P=0.001, U133A microarray) and 3.23-fold (P<0.001, U133A/B microarray) in ccRCC compared with normal kidney tissues, respectively, which was consistent with its protein expression by our immunoblotting analysis 4. Here, ACAT1 is linked to nonpapillary renal cell carcinoma.