Current clinical practice includes several small molecule compounds that target PDE4 for the therapy of lung disease (COPD) (Hatzelmann et al., 2010; Weis and Kobilka, 2018), psoriatic arthritis and plaque psoriasis (Schett et al., 2012) and topically for atopic dermatitis (Callender et al., 2019). Here, PDE4A is linked to chronic obstructive pulmonary disease.