CXCL12 and chronic myelogenous leukemia, BCR-ABL1 positive: CXCL12 may be able to elicit similar concentration-dependent growth suppressive effects on normal and CML CD34+ cells in colony-forming cell assays, but no significant differences were observed on CXCR4 expression and responsiveness to CXCL12-induced increases in intracellular calcium levels between normal and CML CD34+ cells [71].