Thus, our current data provide compelling evidence that PD-L1 expression is notably localized to endothelial cells, which motivated us to establish a model whereby PD-L1 induced by YKL-40 in endothelial cells renders the tumor vasculature resistant to CTL-mediated tumor immunity, thus facilitating tumor vessel-driven malignant transformation (Figure 7). The gene discussed is CD274; the disease is neoplasm.