The emergence of this increase in IL-6 levels could further be linked to disease onset, since IL-6 in serum samples taken at routine intervals confirmed lack of IL-6 increase in the exposed Pax5+/- mice that never developed B-ALL (Fig. 1a-b, Supplementary Table S1 and Supplementary Fig. 1). The gene discussed is PAX5; the disease is precursor B-cell acute lymphoblastic leukemia.