CD274 and neoplasm: As studies involving the expression of CTLA-4 in benign and malignant breast tissues are still in the preliminary stages, we studied expression of CTLA-4 juxtaposed with that of PD-L1, two relevant immune checkpoint proteins associated with breast malignancies, using tissue microarrays in order to elucidate the correlation of CTLA-4 and PD-L1 expression with tumor reactivity and thus the possibility of their use in immunotherapies.