On the other hand, DP1 was shown to be downregulated in the adenoma-carcinoma sequence of patients with colorectal cancer (Kalmar et al., 2015), in intestinal metaplasia and gastric tumor cells from patients with intestinal-type early gastric cancer (Kim et al., 2018), and in artery smooth muscle cells from patients with idiopathic pulmonary arterial hypertension (He et al., 2020). This evidence concerns the gene PTGDR and idiopathic pulmonary arterial hypertension.