CD274 and B-cell chronic lymphocytic leukemia: To address this point, PD-L1 expression was quantified by flow cytometry in MEC-1 transfectants treated for 24 h with 1 μM IT-901, a NF-κB inhibitor that has been proven efficient in inhibiting the transcriptional activity of NF-κB in CLL cells (Vaisitti et al., 2017).