mice demonstrated more severe airspace enlargement induced by cigarette smoke compared with wild-type littermate control mice. Airspace enlargement of Hhip+/- vs. wild-type littermate control mice (Hhip+/+) exposed to cigarette smoke (CS) or air for 6 months as demonstrated by Gill staining (A) and measured by mean alveolar chord length, MCL (B). Mean ± SEM is shown in panel B from 11 to 19 mice per group. Lung mechanics measurements revealed increased lung compliance (C) and decreased tissue elastance (D) in Hhip+/- mice exposed to CS compared to CS-exposed Hhip+/+ mice. *P <0.05 and **P <0.01. Mean ± SEM are shown in each group.