COL18A1 and breast carcinoma: Incubation of human breast cancer cell line MDA-MB-231, which expresses high level of PD-L1 on the cell membrane,19 with culture supernatant of Nc-1-scFv-Fc led to a median fluorescence intensity of up to 7 while the positive control (scFv-Fc produced in CHO) displayed a median fluorescence intensity (MFI) of 13 (Figure 4A).