Lower expression of CD45, an essential modulator of signal transduction pathways in blast cells, is associated with a higher rate of complete remissions at day 29 of B-ALL treatment and high expression of CD45 was associated with unfavourable prognostic factors and worse event free survival of the disease.10,16,26,38 In our experiment, CD45 was down-modulated after exposure to increasing concentrations of daunorubicin, and a dose-dependent up-modulation was observed after the addition of vincristine to the blast cells. Here, PTPRC is linked to acute lymphoblastic leukemia.