Interestingly, the clinically relevant combination of salmeterol and roflumilast induced an inhibition of the roflumilast effect, although both salmeterol and roflumilast are used to treat chronic obstructive pulmonary disease (COPD) (Tyrrell et al., 2015), suggesting that is a possibility that salmeterol affects the ability of roflumilast to inhibit PDE4. The gene discussed is PDE4A; the disease is chronic obstructive pulmonary disease.