LN c-Kit^lo progenitors can complete T-cell development when grown on stromal cells transfected with Wnt4 (OP9-DL1-W4). (A) Sorted DN1 cells (4 × 10³; Lin^–CD44⁺CD25^–Sca1⁺c-kit^lo) from wt LNs were plated on 6-well tissue culture plates containing a confluent monolayer of OP9-DL1 cells transfected or not with Wnt4 and analyzed by flow cytometry after 12 days in culture. Dotted line represents isotype control. (B) Sorted DN4 cells (10⁵; Lin^–CD44^–CD25^–) harvested from wt LNs were cocultured on OP9-DL1 or OP9-DL1-W4 cells and analyzed on day 7. Numbers indicate cell population percentages. The analysis is of 1 representative experiment out of 2.