We also measured MMP-9 concentration at 7 and 13 weeks post WD and / or SHS exposure, and identified elevated plasma concentrations of active MMP-9 in ApoE-/- mice that were both fed WD and exposed to SHS at 13 weeks; whereas total MMP-9 increased in mice exposed to regular diet and SHS at 7 weeks (Fig 5A). Here, MMP9 is linked to Wilson disease.