FN1 and esophageal squamous cell carcinoma: Based on recent studies that have used MSCs to simulate stromal cells in the tumor microenvironment in vivo [34], we created an in vitro model in which the ESCC cell lines, TE-1 and Eca-109, were cultured in MSC-conditioned medium containing high levels of FN, mimicking the effect of mesenchymal cells in the tumor microenvironment.