Nuclear respiratory factor 1 (NRF1) was identified as a transcription activator for the gene encoding cytochrome c. It was later found to play a role in the nuclear control of mitochondrial function . PGC-1 induces the expression of NRF1 and NRF2 . NRF1, along with the coactivator PGC-1, stimulates the promoter of mitochondrial transcription factor A, which regulates mitochondrial biogenensis and function .