Lung tissue immunofluorescence staining demonstrated that the protein levels of SPHK1 were significantly upregulated in the pulmonary artery medial layer smooth muscle cells from different rodent models of pulmonary hypertension, including chronic hypoxia-mediated PH in mice, monocrotaline (MCT)-mediated PH, and hypoxia-mediated PH (HPH) in rats (Figure 1A–D). Here, SPHK1 is linked to pulmonary arterial hypertension.