PPARG and neoplasm: Interestingly, we also found peroxisome proliferator-activated receptors (PPAR) signaling was dramatically activated in gene cluster A. Previous studies have indicated that the activation of PPARγ signaling can reduce the level of insulin-like growth factor-1 (IGF-1) in the blood, which was proven to promote tumorigenesis (36), thus interfering the growth of tumor in pancreas, colon, liver, and prostate (37).