miR-21 has been reported as an oncomir that contributes to motility invasion and metastasis by targeting tumor suppressors such as phosphatase and tensin homolog (PTEN), tropomyosin 1, programmed cell death 4 (PDCD4) and mammary serine protease inhibitor (Maspin) [21]–[23]. The gene discussed is SERPINB5; the disease is neoplasm.