The ILLHPWF sequence is required for Trib1 leukemogenic activity. (A) Leukemia-free survival of animals was compared. Kaplan-Meier survival curves are shown for Trib1 wt (n = 10), Trib1 ΔILLHPWF (n = 10) and pMYs-GFP (n = 8; left), or for Hoxa9/Meis1 + Trib1 wt (n = 8) and Hoxa9/Meis1 + Trib1 ΔILLHPWF (n = 8; right). (B) Representative phenotypes of Trib1-induced AML. Left: leukemic cells in peripheral blood and bone marrow smears (Wright-Giemsa staining). Original magnification, 1000×. Right: flow cytometric analysis. (C) Leukemic cells expressing Hoxa9-Meis1 (H/M), Trib1 wt (wt), Trib1 wild-type/Hoxa9-Meis1 (wt + H/M) and Trib1 ΔILLHPWF/Hoxa9-Meis1 (ΔILL + H/M) were cultured in the absence of IL-3 for 16 hour (−IL-3) and then stimulated with IL-3 for 15 minutes (+IL-3). The cell lysates were immunoblotted with indicated antibodies.