IEX-1 expression in UT7-shAML1 cells. (A) Endogenous AML1 and IEX-1 protein expression in the presence of shAML1. UT7-Mpl cells expressing either control shRNA (lanes 1 and 3) or shAML1 (lanes 2 and 4) were stimulated with 10 nM TPO for 1 hour (lanes 3 and 4) or not stimulated (lanes 1 and 2). Immunoblots were performed with IEX-1– or AML1-specific antibodies. The membrane was stripped and reblotted with antiactin antibody as internal loading control. (B) IEX-1 promoter induction in shAML1-expressing cells. Control UT7-Mpl or UT7-shAML cells were transfected with 400 ng pLucIEXp in the presence or not of 1 μg pME18S-AML1wt. Five hours after transfection, the cells were stimulated with 10 nM TPO and 20 hours later lysed and assessed for luciferase activities. Data represent mean ± SD of 4 independent experiments. *P < .05.