CD274 and neoplasm: Figure 8 presents the results of an IHC assay performed to evaluate the expression of PD-L1 in CT26 tumor-bearing mice at 7 days p.i. On the tumor tissue slide, PD-L1 staining was visualized as a brown 3,3′-Diaminobenzidine (DAB) signal, revealing the heterogeneous expression of PD-L1.