HBEGF and asthma: Furthermore, within this severe asthma cluster it was possible to identify two sub‐clusters: one was characterized by highest IL13 (Figure 7C), ERBB3 and HB‐EGF expression; the other sub‐cluster was characterized by highest amphiregulin (AREG) expression suggesting that there may be distinct sub‐phenotypes of severe asthma that can be defined by different ERBB receptor and ligand combinations.