Among the miRNAs involved in NK/T-cell lymphomagenesis, miR-21 and miR-155 are aberrantly overexpressed and activate AKT signaling via downregulation of the expression of tumor suppressors, including phosphatase and tensin homologue (PTEN), programmed cell death 4 (PDCD4), and Src homology-2 domain-containing inositol 5-phosphatase 1 (SHIP1), in natural killer-cell lymphoma/leukemia [52]. The gene discussed is PDCD4; the disease is leukemia.