HIF1A and pulmonary hypertension: With the murine model of chronic hypoxia-induced pulmonary hypertension, it was found that pulmonary hypertension was promoted in p53 global knockout mice, with increased vascular remodeling, upregulated hypoxia-inducible factor 1 alpha (HIF-1α) expression and downregulated p21 expression in the pulmonary arterial smooth muscle cell (PASMC) (Mizuno et al., 2011).