PPARGC1A and cancer: Second, Feilchenfeldt et al. [13] studied expression levels of all isoforms of PPAR-Υ and transcriptional partners such as PGC1α in patients with different stages of colon cancer, and found that expression levels of PPAR-Υ vary between isoforms and cancer stages, while those of PGC1 were reduced in all cancer samples, with respect to normal samples [13].