Enforced expression of Hoxa9 in hESCs. (A) Schematic representation of the lentiviral vectors used. (B) Bright field and fluorescence images of colonies of empty vector (EV)-expressing and HOXA9-expressing hESCs. (C) Quantitative polymerase chain reaction showing Hoxa9 transcript overexpression in hESCs. (D) Relative Hoxa9 expression levels reached in HOXA9-hESCs as compared with the endogenous HOXA9 expression in CB-CD34⁺, t(4;11) leukemic blasts and the leukemic cell line MV(4;11). Relative expression is shown normalized to EV-hESCs. (E) Western blot analysis demonstrating ectopic Hoxa9 protein expression in hESCs.