EGF and asthma: A severe asthma phenotype with neutrophilic inflammation showed upregulated ERBB3 expression as well as for several EGFR ligands including HB-EGF, epiregulin, and EGF as shown in “IL-17 signature.” Further sub-phenotype analysis revealed that the “IL-13” phenotype and the “IL-17” phenotype had upregulated ERBB3 expression.