Linked to increased mucus production are SPDEF (SAM pointed domain-containing Ets transcription factor) and CLCA1, both also induced by T2 cytokines in the airway epithelium and the latter, as mentioned previously, is also linked genetically to asthma and part of the epithelial T2 signature introduced above [47,177,191,192]. Here, SPDEF is linked to asthma.