CD274 and cancer: A total of 10% and 2% of the PD-L1-positive cancer cells were found on the ex vivo cell preparations obtained from tumor samples sq1 and sq3, respectively, but not on the histological sections obtained from the same tumor samples and simultaneously stained in the immunofluorescence assay using clone ABM4E54 (Abcam) of mouse anti-PD-L1 antibodies (Table 2, Figure 2C).