NFKB1 and B-cell chronic lymphocytic leukemia: Interestingly, the NF-κB inhibitor IT-901 decreased PD-L1 expression in CLL cells transfected with either empty vector or vector encoding the ROS-defective p66ShcQQ mutant to levels similar to CLL cells transfected with wild-type p66Shc (Supplementary Figure S5C, D), supporting the notion that, by restoring ROS production, forced p66Shc expression in CLL cells hampers NF-κB activation, thereby lowering their abnormal PD-L1 expression.