CD34 and acute lymphoblastic leukemia: Our previous studies showed that the effect of SF3B1 inhibition presents with reduced toxicity in hematopoietic progenitor cells, such as CD34+ cells (26), and our present in vivo toxicity analysis failed to detect significant toxicity associated with body or organ weight, blood populations, goblet cell metaplasia, or other gastrointestinal toxicity such as the one previously demonstrated for gamma secretase inhibitor drugs used to block NOTCH1 activity in T-ALL therapy (Fig. 1, I and J, fig.