FLT1 and acute lymphoblastic leukemia: In ALL children in the maintenance phase consisting in daily oral mercaptopurine, weekly oral methotrexate and VCR once a month for 12 months and dexamethasone for 5 days/month for 12 months, circulating endothelial cells (CEC), endothelial progenitor cells (EPC) and endothelial microparticles (EMP), but also VEGF, VEGFR-1 and Ang-2, TSP-1 and regulatory T lymphocytes (Treg) were monitored.