PDE4A and chronic obstructive pulmonary disease: 1997; Essayan 1999; Spina 2008). Specific inhibitors of PDE4 are novel anti‐inflammatory drugs, of which roflumilast was lately introduced for the treatment of COPD and apremilast for plaque psoriasis and psoriatic arthritis (Lipworth 2005; Rabe 2011; Kavanaugh et al. 2015; Papp et al. 2015). Recently, PDE4 was also presented as a beneficial drug target in B‐cell lymphoma, based on the findings of the anti‐inflammatory properties of PDE4 inhibitors (Cooney and Aguiar 2016).