To further study the correlation between exosomal miR-223 and the hypoxic tumor microenvironment, the levels of HIF-1a expression in 28 primary EOCs were measured by immunohistochemical staining, and the 28 EOCs were determined and dichotomized into HIF-1a low (n = 14) and HIF-1a high (n = 14) (Additional file 8: Figure S6A). The gene discussed is HIF1A; the disease is neoplasm.