As a highly conserved RNA binding protein, Lin28 is a specific post-transcriptional inhibitor of let-7 biogenesis and can inhibit the let-7 processing and synthesis. Lin28 is involved in the stem cell proliferation and promote the rapid growth of embryonic stem cells. Lin28 plays an important role in the formation of tumor stem cells. Overexpression of Lin28 promotes the tumor cell proliferation and is associated with advanced human cancers. Lin28 can promote tissue repair.