IL21 and hepatocellular carcinoma: Using a combination of in vitro experiments and in silico regression modeling incorporating the complex interplay between signal transducers and activators of transcription (STAT) and nuclear factor‐kappa B (NF‐κB) induced by the cytokine cocktail, we find that the inclusion of IL‐21 in cytokine mixtures significantly enhances NK cell proliferation and cytotoxicity against hepatocellular carcinoma cell lines.