CD274 and neoplasm: Indeed, YKL-40 and Vim were strongly correlated with PD-L1 expression (p = 4.4 × 10−12 and 1.9 × 10−15), whereas the correlation of the macrophage marker CD68 with PD-L1 levels was weaker (p = 1.7 × 10−5) (Figure 1G), suggesting that mesenchymal tumor cells rather than macrophages are keenly associated with PD-L1 expression.