Lin28B is a member of the lin-28 family. LIN28 protein is a microRNA-binding protein that binds to and enhances the translation of the IGF-2 (insulin-like growth factor 2) mRNA. Lin28B acts as a suppressor of microRNA (miRNA) biogenesis by specifically binding the precursor let-7 (pre-let-7), a miRNA precursor. LIN28 is highly expressed in testis, fetal liver, placenta, and in primary human tumors and cancer cell lines.