Three quarters of patient derived cell lines, all the osteosarcoma standard cell lines (HOS, HOS-143b, SaOS, and U2OS), and two thirds of tumor specimens demonstrated expression of PD-L1 mRNA greater than the negative MCF7 control cell line; however, only a small subset expressed PD-L1 at the same level as the positive control, breast cancer cell line MDA-MB-231. The gene discussed is CD274; the disease is breast cancer.