Since we found that arsenic sulfide can down-regulate THBS1 in HCC cell lines (Figures 2C, D), and THBS1 suppresses immune cell-mediated killing (Figures 4B, C), we hypothesized that arsenic sulfide treatment might counteract the suppressive effect of THBS1 on immune cells. The gene discussed is THBS1; the disease is hepatocellular carcinoma.