PIWIL1 and hepatocellular carcinoma: PIWIL1 overexpression resulted in a remarkable increase in oxygen consumption at both basal and maximal rate of metabolism (Fig. 2b, c), while the increase in ECAR was not as significant (Fig. 2d, e), suggesting that PIWIL1-overexpressing HCC cells may preferably utilize oxidative phosphorylation (OXPHOS) to generate ATP.