SMAD4 and nonpapillary renal cell carcinoma: To this end, we investigated the correlation between AMPK mRNA (AMPKα1, AMPKα2, AMPKβ1, AMPKβ2, AMPKγ1, and AMPKγ2) and phosphoprotein (T172) levels, and the mRNA expression levels of TGF-β (TGFB1) and SMAD (SMAD2, SMAD4) in the TCGA ccRCC database.