LIN28B and neoplasm: The let-7 family is one of the most abundant miRNA families in mammals, and members of this family function as tumor suppressors by targeting multiple oncogenes, including RAS, HMGA2 and c-Myc13, 14.Mammals have two Lin28 homologs, LIN28A (also known as Lin28) and LIN28B, both of which play similar suppressive roles in let-7 biogenesis15, 16, 17.