HMGA2 and B-cell chronic lymphocytic leukemia: Part of this relationship is physical; let-7 binds to coding regions and untranslated regions (UTRs) of genes critical for DNA replication such as programmed cell death ligand 1 (PD-L1) [53] and high mobility group AT-hook 2 (HMGA2) [57], as well as apoptotic genes such as caspase 3 [58], B-cell CLL/lymphoma (BCL) [59,60], and caspase 8 [61].