In one of such studies examining the cytokine and GF concentrations in the PB of children treated for ALL, it was found that the levels of 33 of the 51 examined cytokines and GFs, including GM-CSF, G-CSF, VEGF, and PDGF, were significantly higher as compared to healthy children, while no significant differences were observed for b-FGF levels [42]. This evidence concerns the gene CSF2 and acute lymphoblastic leukemia.