Upon USP28 inhibition using AZ1 in primary CLL cells (n = 10; Supplementary Table 3) we observed decreased expression of several NOTCH1 target genes including FYN, ZMIZ1 and NRARP which were previously validated to be CLL specific [14, 15, 17] (Supplementary Fig. 13). Here, USP28 is linked to B-cell chronic lymphocytic leukemia.