The expression gene signatures of LUAD and LUSC do not have any common gene, however they share eight common pathways which are mostly metabolic pathways: Central carbon metabolism in cancer, Glycolysis/Gluconeogenesis, HIF-1 signaling pathway, Pyruvate metabolism, PPAR signaling pathway, Amino sugar and nucleotide sugar metabolism, TNF signaling pathway and Pathways of neurodegeneration—multiple diseases. Here, PPARA is linked to cancer.