THY1 and idiopathic pulmonary fibrosis: In addition, DNA hypermethylation at promoter regions is considered a crucial contributing factor for downregulation of the IPF suppressor genes such as THY1 (Thy-1 antigen), CAV1 (Caveolin 1), PTEN (Phosphatase and tensin homolog), and PTGER2 (Prostaglandin E receptor 2), which are known to regulate important cellular processes.