The mutated RUNX1 protein in Runx1f/fmice was nonfunctional. (A) Immunofluorescent staining of bone marrow cells from the indicated mice 2 weeks after pIpC treatment to detect the colocalization between RUNX1 or the mutated RUNX1 and CBFβ/CBFβ-SMMHC. (B-D) 293T cells were transfected with the indicated plasmids, and immunofluorescence staining was performed to detect the localization of the indicated proteins. The labels on the left side of the pictures indicate the plasmids transfected into the cells and the labels on top of the pictures indicate the observed proteins at the appropriate microscope filter settings. (E-F) Luciferase reporter assay in 293T cells transfected with a CSF1R promoter-driven luciferase reporter plasmid and plasmids encoding the indicated proteins. (E) Relative activities (mean ± SEM) were determined based on 3 independent experiments. ****P < .0001. (F) Representative expression levels of the transfected proteins for this reporter assay by western blot analysis.