Committed T-cell precursors efficiently differentiate in the absence Notch/DL signaling. (A) Freshly isolated CD34⁺CD1⁺ thymocytes were cocultured on OP9-control and OP9-DL1 stromal cells. Dot plots show CD4, CD8β, and CD1 profile in flow cytometry after 6 days of coculture. Numbers in dot plots indicate the percentage of cells in the indicated areas. (B) Average total number of cells (± SD) and CD4⁺CD8β⁺ cells generated from OP9 cocultures as shown in panel A. Data are derived from 3 independent experiments.