CXCL12 and acute myeloid leukemia: However, after CXCL12 induction, shHCK CD34 positive cells obtained from AML patients exhibited lower migration (average: 13.3%; range 5.9–16.1%) compared to shControl CD34 positive cells (average: 53.1%; range 50.9–57.7%; P < 0.0001) (Figure 2B).