PTGS2 and chronic obstructive pulmonary disease: On day 0, genes having a lower expression level in cells on COPD compared to normal scaffolds included the HGF receptor MET19, FOS-related antigen 1 (FOSL1)20, low density lipoprotein receptor (LDLR)21 and prostaglandin-endoperoxidase synthase 2 (PTGS2)22 (also known as cyclooxygenase 2).