Furthermore, the critical role of Myd88 downregulation for B-ALL development in Pax5+/− mice was further confirmed by both the lack of B-ALL development in Pax5+/+;Myd88+/− mice under natural infection exposure (0 out of 26) (Fig. 3b) and the appearance of B-ALL in Pax5+/−;Myd88+/− mice even in the absence of exposure to infections (5 out 8, 62.5%) (Supplementary Fig. S9), a condition where Pax5+/− mice never develop B-ALL3. This evidence concerns the gene PAX5 and infection.