Knockdown of Hemgn by shRNA decreased secondary CFU-C in HOXB4-transduced BM cells. (A) Western blot analysis for Hemgn expression in MEL cells transduced with panel of shRNA lentiviral vectors. A scrambled control sequence was included as well as mock-transduced cells. shRNA-6 was the most effective construct and used in the CFU-C experiments shown. (B) In these experiments, HOXB4-transduced cells were then transduced with either the shRNA-6 or the scrambled control vector and assayed in a secondary CFU-C assay. The secondary colony number per 10⁴ plated cells is shown for HOXB4 only, for HOXB4 transduced with shRNA-6, and for the scrambled control. Three independent experiments were performed, and the decrease in secondary colony number with the shRNA was highly significant. *P < .05.