In addition, SphK1 over-expression in VSMC increased IL-6 and signal transducer and activator of transcription (STAT)1 gene expression and up-regulated the expression levels of pro-inflammatory factors IL-8/33 and chemokines CXCL-6/8, as was found in PAH patients (Hirafuji et al., 2002; Bai et al., 2021). This evidence concerns the gene SPHK1 and pulmonary arterial hypertension.