CCR4 and allergic asthma: In the field of classic inflammatory lung pathologies, therapeutic inhibition of CCR4 signaling has mainly been discussed as a potential treatment strategy for allergic asthma so far, while the interplay between CCR6 and its ligand CCL20 recently arose as another promising target for a numeric regulation of local ILC2 pools in the inflamed lung tissue, which might be of particular relevance for the clinical management of CF.