SF3B1 and leukemia: Although several SF3B1-mutant isogenic cell lines were previously generated from B-cell precursor leukemia cells, myeloid leukemia cells, murine embryonic stem cells, or induced pluripotent stem cells (Darman et al, 2015; Murthy et al, 2019; Dalton et al, 2019), our cell lines are the first isogenic CLL cell lines harboring WT and mutated SF3B1 reported so far.