Since it has been shown that the expression of P-STAT3 regulates arginase 1 expression levels and activity in MDSCs[49], and since we observed a higher activity of arginase 1 in tumor-derived MDSCs, we cannot exclude that AZD1480 has differential effects on the function of either tumor-or spleen-derived MDSCs. The gene discussed is STAT3; the disease is neoplasm.