Decrease in primary CFU-C proliferation due to expression of AML1-ETO.

(A) Human HPCs were transduced with the indicated retrovirus and 2 days later were analyzed for GFP expression and plated in methylcellulose culture. Colonies were counted 2 weeks later, and GFP expression in the colonies was evaluated microscopically. The average of 2 independent experiments is shown. (B) HPCs were transduced as in panel A; the cells were sorted for GFP expression 2 days after transduction and immediately plated in methylcellulose culture. PBPCs represent mock-transduced HPCs. Colonies were counted after 2 weeks, and the average of triplicate plates is indicated. (C) A representative GFP⁺ colony is shown for both the control and the AML1-ETO–transduced HPCs. The top panels are phase-contrast images, and the bottom panels show fluorescent images. The magnification is 400 ×.