A prior study reported that lymphoblastic leukemia cells in co-culture were sensitized to vincristine by a CXCR4 inhibitor through the upregulation of Bax (33). However, there are conflicting data in the published literature. For example, a 2013 study revealed that CXCL12 stimulation resulted in increased apoptosis in AML cell lines, mediated by Bcl2 family members (34). Here, CXCL12 is linked to acute myeloid leukemia.