HK2 and cancer: In spite of frequent HK2 expression in various cancers [2], hepatocellular carcinomas (HCCs) exhibit heterogeneous expression of HK2 [3–5], which contributes to heterogeneous 18F-2-fluoro-2-deoxy-D-glucose (18F-FDG) uptake in positron emission tomography (PET) scan [6, 7] and therefore reduces the clinical usefulness of 18F-FDG PET in HCCs [8, 9].