ATR and B-cell chronic lymphocytic leukemia: Using CRISPR/Cas9 targeting, the NOTCH1-PEST protein domain in Mec-1 a CLL cell line showed low levels of DUSP22 expression which significantly correlates with the spleen and the brain homing suggesting that NOTCH1 mutation occurs specifically on the PEST domain which could act as a major driver in CLL leukemogenesis with bad prognosis (Arruga et al., 2017).