F/P fusion promotes differentiation and proliferation of BMMCs and increases survival after cytokine depletion. (A) F/P-expressing or mock vector–transduced BMMCs were cultured in the absence of cytokines for 48 hours, and then the survival of BMMCs was assessed by annexin V and 7-AAD using flow cytometry. Data represent means (± SEM) of BMMCs that were annexin V and 7-AAD double negative. *P < .05 (n = 3, from 1 representative experiment of 3). (B-D) BMMC output associated with FIP1L1/PDGFRα expression. F/P-transduced (■) or mock vector–transduced (▲) 5-FU–treated BM HSC/Ps were cultured in the absence (B) or presence of recombinant stem cell factor (rSCF, 100 ng/mL; C) or rIL-3 (100 ng/mL; D). MC content of cell cultures from panels B through D was assessed by flow cytometry of EGFP⁺/c-kit⁺/Fc∈RIα⁺ cells. The data are depicted as fold expansion (MC [EGFP⁺/c-kit⁺/Fc∈RIα⁺cell] numbers divided by seeded HSC/P numbers in indicated periods). *P < .05; **P < .01; and ***P < .001, compared with mock vector (EGFP⁺) MC cells (n = 3 from 1 experiment representative of 2 or 3 experiments).