EPO and gastrointestinal disease: Furthermore, 5-methoxytryptamine might play a role in cancer, tumor morphology, gastrointestinal disease, hepatic system disease, inflammatory disease, cardiovascular disease (Fig. 8D) etc. through colorectal cancer metastasis signaling, tumor microenvironment pathway, apoptosis signaling, MYC mediated apoptosis signaling, erythropoietin signaling pathway, LXR/RXR activation (Fig. 8B) etc. Meanwhile, GABA, LysoPA(18:1(9Z)/0:0) and L-Targinine, the unique metabolites of RA EP, were closely related to RA target genes.