EL08-1D2 stroma and cytokine (Flt3-L, IL-7, c-kit-L, IL-15, IL-3) cultured cells were harvested, counted and analyzed by flow cytometry. (A) Absolute numbers of cultured eGFP+(◆) and ICN+(▲) derived CD56+CD3− NK cells calculated per 100 plated cells were compared at weekly intervals. In the presence of stroma, activated Notch1 conferred an early growth advantage to cultured cells compared to eGFP+ control cells (○) at days 14 and 21 (*P=0.005; mean of 3 independent experiments shown). (B) Stroma cultured eGFP+ cells and ICN+ cells were harvested at day 28 and compared for expression of CD56 and CD7 (gated on CD56+CD3− cells). CD7 was highly expressed only on ICN+ cells (representative of 6 experiments shown).