IL7 and precursor B-cell acute lymphoblastic leukemia: Moreover, B-ALL arising in Pax5-deficient mice exposed to infection10 or in mice with combined loss of Sh2b3 and Trp53 (ref. 11) involves an IL-7 hypersensitive pre-leukemic stage, and IL-7Rα is required for B-ALL developing in mice from the combination of Stat5 activation and Pax5 haploinsufficiency12.