HMOX1 and pulmonary hypertension: HO-1 is also influential in the pulmonary vasculature: hypoxic induction of pulmonary hypertension (and hence right ventricular dilation) was far worse in HO-1−/− mice [55], and targeted pulmonary over-expression of HO-1 prevents inflammation and pulmonary vessel wall hypertrophy (including VSMC proliferation) in response to hypoxia [31].