CD274 and neoplasm: Stromal PD-L1 and tumor PD-L1 expression appear to have independent, suppressive effects on anti-tumor immunity (Lau et al., 2017), but we noted that the expression of the pan-leukocyte marker PTPRC (coding for CD45) and lymphocyte marker CD3E were only modestly increased in the high RAS pathway activity cohort, indicating that the differential in PD-L1 expression is not likely to be solely attributable to a higher degree of leukocyte infiltration in the tumor microenvironment (Figure 6A).