These expression patterns contrast sharply with those of LCK which is highest in T-ALL as expected (Figure S6C), RUNX1 which is equally expressed in T- and B-ALL but not in brain tumors, or JAK1, encoding a non-receptor tyrosine kinase, which is higher in B-ALL compared to the other two groups, and finally NAXE, encoding a metabolic enzyme which is expressed in all three types of pediatric cancers with modest but significantly lower levels in B-ALL (Figure S6B). Here, JAK1 is linked to precursor B-cell acute lymphoblastic leukemia.