 Liver stem cells have been identified as bridging the gap between liver development, regeneration, and cancer. Studies on embryonic liver development have provided the basis for differentiating human embryonic stem cells and induced pluripotent stem cells into hepatic cells. This knowledge has improved our understanding of the cell biology of proliferation and differentiation in the liver, which can be applied to drug testing, bio-artificial livers, and transplants. Parallel advances in cancer research have revealed similarities between the mechanisms regulating liver development, regeneration, and cancer, leading to new targeted therapies for liver cirrhosis and primary liver cancers. This article was authored by Janet W. C. Kung, Ian S. Curry, Stuart J. Forbes, and others.