Finally, with the aim of identifying a proteomic signature that can help in differentiating stage IV T-LBL from T-ALL patients, we successfully identified six proteins, namely ERK1/2 T202/Y204, AKT S473/TOT, mTOR S2448/tot, FAK Y397, P21 and BAX whose expression/activation was able to distinguish stage IV T-LBL from T-ALL. The gene discussed is PTK2; the disease is acute lymphoblastic leukemia.