Wnt pathway activation is required for leukemia cell amplification. (A) The 149.4, 149.8 and T29 cell lines were transduced with Mig-R1 or Mig-ICAT. Two days later (defined as day 0), GFP⁺ and GFP⁻ cells were sorted and cocultured for 7 days. Cumulative numbers of GFP⁺ cells are plotted over 7 days of coculture. (B) Flow cytometry analysis of 149.8 GFP⁺ and GFP⁻ cells in the cocultures described in (A) are shown at days 0 and 7. (C) The survival curve of mice transplanted with 10⁴ GFP⁺ or GFP⁻ 149.8 cells from cultures transduced with Mig-R1 or Mig-ICAT. (D) Western blot analysis of LEF1 expression in total extracts from control, preleukemic, and leukemic thymocytes. All panels are representative of 2 independent experiments.