IL6 and hepatocellular carcinoma: In addition to HO-1 blocking the ROS synthesis after H2O2 or pyocyanin stimulation in human hepatoma cells (Figure 2), our data supported the belief that upregulation of HO-1 plays a pivotal role in cell adaptation to oxidative stress and cytokine insults, and the negative feedback between HO-1 and IL-6 might be partly due to the anti-inflammatory effect of HO-1 [14].