MiR-21 has been demonstrated to accelerate tumorigenesis by targeting tumor suppressor genes, including phosphatase and tensin homolog (PTEN), tropomyosin 1 (TPM1) and programmed cell death 4 (PDCD4). This, in turn, increases tumor cell growth, migration and invasion (21, 22, 27-26). The gene discussed is PDCD4; the disease is neoplasm.