FoxO1 inhibitor induced significant apoptosis (85%-90% at 10 days; P < 0.0001) in primary CLL cells cocultured with HS5 stromal cells or with HS5 stromal cells engineered to produce T cell factors CD40L, IL-4, and IL-21 (Figure 7, A and B) (47). This evidence concerns the gene IL21 and B-cell chronic lymphocytic leukemia.