Flt3-ITD partially inhibits growth suppression by PLZF. (A) PLZF expression was confirmed in the absence of tetracycline (tet) in tet-off PLZF-inducible U937 cells by immunoblot. (B) Tet-off PLZF-inducible U937 cells were electroporated with the MSCV-GFP control plasmid (vec) or MSCV-Flt3-ITD-GFP (Flt3-ITD) plasmid. Three days after transfection, GFP-positive cells were sorted and plated in triplicate or quadruplicate. PLZF expression was induced in the indicated cells by tetracycline withdrawal. Cell proliferation as quantified by tetrazolium reduction was compared with a baseline of absorbance 2 days after PLZF induction. (Left) Cell growth in the absence of PLZF expression. (Right) Cell growth in the presence of PLZF expression. Two independent experiments are presented as mean values ± standard deviation.