GSK3B and acute lymphoblastic leukemia: In order to determine whether GSK3β activity has an impact on the proteolysis of other MALT1 substrates, we established Jurkat T-ALL cell clones either stably expressing a control shRNA (Jurkat-shControl cells) or a GSK3β-specific shRNA (Jurkat-shGSK3β cells) leading to a distinct reduction of GSK3β expression and to increased β-catenin protein levels (Fig. 1A, Supplemental Fig. 1A).