YY1 and acute myeloid leukemia: In acute myeloid leukemia, YY1 negatively regulates let-7a, which inhibits the expression of the anti-apoptotic protein B-cell lymphoma-extra-large (BCL-xL) [65]; instead, miR-7 may silence YY1 and KLF4 mRNAs, contributing to chemoresistance [66].