S100A1 and pulmonary arterial hypertension: Teichert-Kuliszewska et al. demonstrated that S100A1 is also expressed in the lung vascular endothelium, and its deficiency in knockout (KO) mice leads to increased right ventricular (RV) systolic pressure (RVSP) as well as aberrant endothelial-dependent relaxation in response to acetylcholine and decreased availability of nitric oxide (NO) thus predisposing to pulmonary hypertension [61].