CD34 and acute lymphoblastic leukemia: Recently, one study has revealed that the splenic microenvironment reduces apoptotic sensitivity of T-ALL cells to the inhibitors of B-cell lymphoma 2 (BCL2); interestingly, a small population of CD34+ cells are enriched in the splenic niche following the treatment of BCL2 inhibitors [61], suggesting that the spleen provides a sanctuary microenvironment for the immature T-ALL subset.