PTEN and esophageal squamous cell carcinoma: Moreover, the expression of PTEN, which inhibits the PI3K/AKT signaling pathway, was down-regulated in macrophages incubated with ESCC-derived exosomes (Fig. 6e and f), suggesting that ESCC-derived exosomes induced M2 macrophage polarization via the inhibition of PTEN and activation of the PI3K/AKT signaling pathway, and then promotes angiogenesis.