CD274 and non-small cell lung carcinoma: For 14 tumors, we measured PD-L1 mRNA expression significantly above the detection threshold, and in this cohort, there was a PD-L1v4/PD-L1v1 mRNA ratio comparable to the observations in NSCLC cell lines, as well as the presence of a negative correlation between the PD-L1v4/PD-L1v1 mRNA ratio and total PD-L1 mRNA expression (Figure 4A).