an RNA-binding protein that binds to and enhances the translation of the IGF-2 (insulin-like growth factor 2) mRNA. Lin28 binds to the let-7 pre-microRNA and blocks production of the mature let-7 microRNA in mouse embryonic stem cells. In pluripotent embryonal carcinoma cells, LIN28 is localized in the ribosomes, P-bodies and stress granules. LIN28 is highly expressed in human embryonic stem cells[14] and can enhance the efficiency of the formation of induced pluripotent stem (iPS) cells from human fibroblasts. LIN28 is a marker of undifferentiated human embryonic stem cells and has been used to enhance the efficiency of the formation of iPS cells from human fibroblasts.