CD274 and breast cancer: To investigate the function of sPD-L1 from MDA-MB231 on the differentiation of CD19+ B cells, we established MDA-MB231 cells incubated with CD19+ B cells activated by LPS in DR or IDR conditions compared to PD-L1–deficient MCF-7 breast cancer cells (PD-L1lo BC) (Supplemental Figure 1A) (Figure 5A).