AKT activity is important for NOTCH-induced megakaryopoiesis from CMPs but not from LSK cells. (A) Flow cytometric analysis of purified wild-type LSK cells or CMPs infected with an empty control vector (MIG) or an inactive KD-AKT allele and plated on OP9-DL1 stroma for 6 days. Contour plots obtained from FACS analysis show a representative of 4 independent experiments. (B) Bar graphs represent mean ± SEM from 4 independent experiments described in panel A. (C) LSK cells from Mpl^−/− and wild-type control animals were flow-sorted and cocultured with OP9-DL1 stroma for 6 days. A representative analysis, gated on CD45⁺ hematopoietic cells, is shown. (D) Bar graphs represent mean ± SEM from 2 independent experiments described in panel C.