EPHB4 and esophageal squamous cell carcinoma: Since M6PR-rich Exo did not facilitate the invasion of ESCC cells (Supplementary Figure S5G), we examined whether the other obviously upregulated protein in SRGN Exo, i.e. EphB4, which was positively correlated with SRGN in the serum of patients with ESCC (Supplementary Figure S6), mediated the pro-invasive effect of SRGN.