Thirty-eight peptides were differentially phosphorylated between IKZF1 deleted (N = 13) and IKZF1 wild type (N = 31) pediatric Ph− BCP-ALL patients: phosphorylation of 14 peptides was higher in the IKZF1 deleted group and 24 peptides showed reduced phosphorylation intensities (P ≤ 0.05, Fig. 2b, Additional file 3: Table S2). Here, OPN1SW is linked to acute lymphoblastic leukemia.