PPARGC1A and neoplasm: Both Walker 256 rat tumor cells and tumor biopsies from rats fed the Leu-rich diet showed an increase in oxygen consumption, which was accompanied by an upregulation of mitochondrial genes, including proliferator-activated receptor γ coactivator-1α (PGC-1α), nuclear respiratory factor-1 (NRF-1), cyclooxygenase (COX) 5a, citrate synthetase (CS), and cytochrome C, indicating enhanced mitochondrial biogenesis and oxidative phosphorylation (OXPHOS) (Figure 2).