JAK2V617F-harboring bone marrow cells induce DNA damage response in neighboring normal cells in a paracrine manner. (A) Schematic representation of the following experiments. Murine bone marrow c-Kit⁺ cells were retrovirally transduced with JAK2V617F-IRES-GFP or control GFP and transplanted into sublethally irradiated mice. The reconstituted bone marrow cells were sorted on the basis of GFP positivity. SSC, side scatter. (B) Representative immunofluorescence images for γH2AX foci formation (Alexa Fluor 647: green) in GFP^+/−Lin^–c-Kit⁺ cells in the MPN or control bone marrows. Nuclei were stained with 4,6 diamidino-2-phenylindole (DAPI) (blue). (C) Average distribution of the numbers of γH2AX foci per nucleus is shown. More than 100 cells were counted in individual specimens. Experiments were performed for 3 mice in each model. Scale bars: 10 μm.