According to our model prediction, the majority of the cells that express PD-L1 in the tumor were cancer cells, and since the PD-L1 density in the model was defined as the average PD-L1 level on cells in the tumor, we approximated the PD-L1 expression by dividing the model-predicted PD-L1 density by a theoretical maximum level of 1770 molecules/μm2. Here, CD274 is linked to cancer.