SOD1 and hepatocellular carcinoma: Interestingly, isobologram analysis showed that the combined effect of HCQ with sorafenib treatment synergistically inhibited and re-sensitized HCC-resistant cell proliferation (CI values < 1) to sorafenib, as shown in Figure 6C, and induced the expression of apoptotic markers such as c-PARP, c-caspase-3, and SOD1 in sorafenib-resistant cells (Figure 6D).