NFKB1 and leukemia: In addition, following the immunoprecipitation of MALT1 from the Jurkat lysates, we observed that lesbicoumestan-treated MALT1 was conjugated by K48-linked poly Ub chains, leading to MALT1 degradation and the subsequent downregulation of phospho-IκBα and phospho-p65 expression levels; this result suggests that MALT1 stability is critical in delivering the signal to NF-κB cell activation in leukemia (Figure 4C,D).