MCL cells with ATM deficiency could be more sensitive to PRMT5 inhibition than those with proficient ATM. In line with this hypothesis, we found that ATM-deficient PDX tumors (Fig. 5m, n) as well as cell lines Granta-519 and Maver-1 (Fig. 5a, b, d, e), are sensitive to PRMT5 inhibition. Here, ATM is linked to mantle cell lymphoma.