CTLA4 and neoplasm: Moreover, we identified substantial positive correlations between the expression of A3s genes and immune checkpoint genes (CTLA-4 and PD-L1) in the majority of tumor types, including BRCA, CESC, GBM, LGG, HNSC, KIRC, THCA, and USC (as depicted in Figures 4D, E; P < 0.05).