Effect of BRAF^V600Eon cell proliferation and apoptosis in vivo. (A) Proliferation (EdU incorporation) and apoptosis (annexin-V binding) were analyzed by flow cytometry in normal B cells (CD5^–CD19⁺) from the spleens of preleukemic transgenic mice (∼2 months old; n = 6 for both BRAF^WT×TCL1 and BRAF^VE×TCL1). (B) The same experiment was conducted using healthy mice engrafted with leukemia cells pooled from 3 leukemic donor animals after the onset of leukemia (>10% CD19⁺CD5⁺ cells in peripheral blood of the CD45⁺ population) (n = 18 for BRAF^WT×TCL1 EdU and n = 24 for annexin-V; n = 14 BRAF^VE×TCL1 for both EdU and annexin). (C) The experiment in (B) was repeated using single donors for each genotype (EdU: n = 8 for BRAF^WT×TCL1 and n = 9 for BRAF^VE×TCL1; annexin-V: n = 8 for BRAF^WT×TCL1 and n = 19 for BRAF^VE×TCL1). The horizontal bars represent the median.