IL-9 overexpression was also observable in leukemic cells from Eμ-TCL1 with overt leukemia, along with a profound decrease in p66Shc expression, and further increased in leukemic cells from Eμ-TCL1/p66Shc−/− mice [15], demonstrating that p66Shc participates in the control of IL-9 expression (Figure 2). Here, IL9 is linked to leukemia.