Inhibitory effects of TGF-β1 and TNF- on colony formation from single sorted CD34⁺⁺⁺kit^Lo/− (I), kit⁺(II), and kit⁺⁺ (III) cells transduced withc-kit cDNA or mock control and growth in the presence of full dosages of IL-3, GM-CSF, Epo, and SLF with or without TGF-β1 (5 ng) or TNF- (20 ng) per mL in the serum-depleted cultures. Results are expressed as percent wells with growth from a total of 96 wells per point from 3 separate experiments. Significant differences for cells transduced with c-kit cDNA from that with mock control;^aP < .05; significant differences for cells incubated with TGF-β1 or TNF- from medium control;^bP < .05.