ATM and B-cell chronic lymphocytic leukemia: In order to evaluate how monoallelic or biallelic ATM and/or TP53 lesions contributed to the clonal dynamics of CLL in an in vivo setting, GFP and/or RFP‐tagged HG3WT and HG3 TP53MUT cells, as well as HG3‐del(11q), HG3‐del(11q) TP53MUT, and HG3‐del(11q) ATMMUTTP53MUT were mixed at a ratio 1:1 and injected into NSG mice (Figures 4A and 4B).