PDE4A and chronic obstructive pulmonary disease: Non-/PAN-selective inhibitors of PDE4 enzymes produce a range of potential therapeutic effects in animal models, including potent anti-inflammatory, memory- and cognition-enhancing, or cardiovascular effects, and several PAN-PDE4 inhibitors have already been approved for clinical use for chronic obstructive pulmonary disease (COPD) and psoriasis [13,14,15,16,17,18,19,20].