In addition, this increase in IL-6 was not observed in mouse models where the appearance of B-ALL is triggered by infection exposure but is not linked to a congenital Pax5 alteration, like in Sca1-BCR-ABLp190 and Sca1-ETV6-RUNX1 mice where the second hit does not involve Pax5 inactivation (Fig. 1c)21. Here, BCR is linked to infection.