Major basic proteins are located in the core: MBP-1, encoded by PRG2; and MBP2, a homolog of MBP-1 which has been described as being less cationic and for being strictly eosinophilic specific (as MBP-1 is also present in basophils and mast cells) [8], being both proteins involved in asthma pathogenesis; while the matrix contains eosinophil cationic protein (ECP, encoded by RNASE3), eosinophil peroxidase (EPX, encoded by EPX), and eosinophil-derived neurotoxin (EDN, encoded by RNASE2) with roles in airway remodeling in asthma [9] (Figure 1 and Figure 2). The gene discussed is EPX; the disease is asthma.