In pediatric patients with acute leukemia, SDF-1α serum levels differed depending on whether they were evaluated in PB or BM serum (decreased expression) or MSC supernatants at diagnosis (decrease not evident) compared to the remission and control groups [15]. The above, combined with our findings, further support the notion that leukemic cells do not affect CXCL12 production and the decrease reported in serum cannot be attributed to the productive capacity of MSCs. This evidence concerns the gene CXCL12 and acute leukemia.