Characterization of E26- and AEV-transformed clones.

(A) JS4⁺ cells were infected with each of the 2 viruses, transformed colonies isolated after 6 days (AEV) or 10 days (E26), and expanded until day 17, when they were analyzed by FACS. The top 2 rows represent cells transformed by E26; bottom row, by AEV. (B) Hemoglobin expression in E26-transformed clones. PCR indicates ethidium bromide–stained reverse transcriptase–PCR products; probe, autoradiographs of bands hybridized to an ε-globin– or β-globin–specific probe. Samples (tested in duplicate) correspond to E26-transformed clones 1 and 2. Bone marrow cells from a 2-week-old chick and 3-day yolk sac were used as controls. M indicates marker DNA used to identifiy size of PCR fragments. (C) Histograms showing the proportion of cells positive for MEP21, JS4, and hemoglobin in 4 E26-transformed colonies at day 17 (dark gray bars) and day 24 (hatched bars) after infection. Clones were ordered according to their content of MEP21⁺ cells.