MSCV retroviruses were created with GFP fused in-frame with exons 1–5 of CBFB (CBFB-GFP), CBFB::MYH11 (CBFB:GFP-MYH11), or the portion of MYH11 involved in the CBFB::MYH11 fusion (GFP-MYH11). EV indicates the retrovirus with GFP alone. Lineage-depleted mouse bone marrow cells were transduced with retrovirus and harvested 4–7 days after transduction for immunofluorescence. DAPI staining (identifying the nucleus) is shown in blue, and yellow dotted lines outline the nucleus. GFP (detected directly) is in green, and RUNX1 (detected with antibody staining) is in red. Overlaps between GFP and RUNX1 signals are yellow. In EV-transduced cells, RUNX1 is localized to the nucleus. CBFB-GFP is predominantly localized to the nucleus, where it colocalizes with RUNX1. However, CBFB::MYH11-GFP is predominantly localized in cytoplasmic aggregates; in these cells, RUNX1 is mislocalized from the nucleus to the cytoplasm. GFP-MYH11 forms large aggregates in both the nucleus and the cytoplasm, and does not colocalize with RUNX1. Images shown are representative of 2–4 independent experiments. Scale bars: 10 μm.