HCC induces over 50% of CD3− CD56+ NK cells to express cell surface CD25 and intracellular IFN-γ (median 19·9%, range 1·6–57·5, Fig. 1a–c) and has a significant, but much less marked, effect on CD107a expression (median 2·5%, range 0·001–9·0, Fig. 1a,d,e). The gene discussed is NCAM1; the disease is hepatocellular carcinoma.