PDE4C and chronic obstructive pulmonary disease: During the pathogenesis of COPD, CS exerts modulates effects on various proteins and signalling pathways, influencing gene expression patterns such as poly ADP‐ribose polymerase 1 (PARP1), phosphodiesterase 4A (PDE4A), phosphodiesterase 4B (PDE4B), phosphodiesterase 4C (PDE4C), phosphodiesterase 4D (PDE4D), prostaglandin D2 receptor 2 (PTGDR2), heme oxygenase 1 (HMOX1), and matrix metallopeptidase 1 (MMP1).