CD274 and breast cancer: In line with this assumption, we observed increased expression of IL-10 and PD-L1 in peritoneal macrophages followed by treatment with tumor-conditioned culture medium (TCCM) obtained from mock-transfected 4T1 breast cancer cells, whereas an increase in IL-10 and PD-L1 expression was not observed in those treated with TCCM from NDRG2-transfected cells (data not shown).