SERPINB5 and cancer: Serine peptidase inhibitor 5 (SERPINB5) gene was originally reported to act as a tumor suppressor gene in epithelial cells, suppressing the ability of cancer cells to invade and metastasize to other tissue.24 Maspin (mammary serine protease inhibitor) is a protein encoded by SERPINB5 gene.25 Several studies have investigated the role of maspin and found its function in cell proliferation.26 Kim et al27 analyzed the global CpG methylation difference between 2 radio‐sensitivity opponent nonsmall cell lung cancer (NSCLC) cell lines.