S100A9 and pulmonary arterial hypertension: Correspondingly, data of immunostaining and Western blot showed that the protein expression of S100A9 significantly increased in the lung tissues of SuHx‐induced PH mice (Figure 3F,G), chronic hypoxia‐induced PH mice and rats with MCT‐induced PAH (Figure S3A,B, Supporting Information) compared to those of control animals.