CD274 and cancer: Namely, HLA-DR expression level in CTLs was negatively correlated with the expression level of TGF-β (r = −0.45, p < 0.01), which increases the metastatic profile; PD-L1 (r = −0.44, p < 0.0001), that inhibits infiltration and/or activation of CTLs (23, 24); IL-6 (r = −0.51, p < 0.001), IL-8 (r = −0.56, p < 0.001) and IL-1β (r = −0.49, p < 0.001) that are inflammatory cytokines that may act as growth factors to sustain cancer cell proliferation and invasion (25–27).