In fact, transforming growth factor-β must be present along with transforming growth factor-α to stimulate proliferation of fibroblasts.13 Homma et al. 22 found that exposure or colonisation by Staphylococcus aureus in the airway may enhance the remodelling of tissue through a transforming growth factor-α-dependent induction of matrix metalloproteinase-1 expression and may, thereby, promote remodelling in airway diseases in which Staphylococcus aureus is implicated, such as asthma and chronic rhinosinusitis with nasal polyps. Here, MMP1 is linked to nasal cavity polyp.