MMP12 and asthma: Taken together, the present study emphasizes (1) that even in utero exposures to low levels of SHS (3mg/m3) can potentially lead to the development of serious asthma symptoms in adulthood (Figures 5–7), and (2) that targeting the regulation of MMP12 could be a potential therapeutic approach related to in utero SHS exposure-induced enhancement of asthmatic responses.