[1] Weill Cornell Med Coll, Dept Pediat & Cell & Dev Biol, New York, NY 10021 USA
[2] Imperial Coll London, Dept Haematol, Fac Med, London W12 0NN, England
[3] Mem Sloan Kettering Canc Ctr, New York, NY 10021 USA
[4] Champalimaud Fdn, Champalimaud Metastasis Ctr, P-050094 Lisbon, Portugal