CD274 and neoplasm: ,48 Furthermore, up-regulation of PD-L1 signaling has been also shown to be directly promoted by cytokines involved in the antitumor immune response.49, 50, 51 Given these findings, stromal PD-L1 expression might reflect an immunogenic tumor microenvironment that is able to suppress cancer growth and thus explains the association of improved clinical outcome found in our study.52