Selective inhibition of PDE4 has been predicted to have potential anti-inflammatory activity in lung inflammatory pathologies, such as asthma and chronic obstructive pulmonary disease (COPD), but early on inhaled corticosteroids (ICS) become the anti-inflammatory of choice in asthma, while the use of oral PDE4 inhibitors was complicated by variable activity and the presence of significant side effects, in particular gastrointestinal. The gene discussed is PDE4A; the disease is chronic obstructive pulmonary disease.