Decreasing Ctnnb1 levels in Apc^del/+ mice reverses the MDS phenotype. Histology of hematopoietic tissues from a representative Apc^del/+ mouse (A, mouse 3938) euthanized when displaying severe signs of anemia (241 days) vs an Apc^del/+, Ctnnb1^del/+ mouse (B, mouse 8455), and an Apc^fl/+, Ctnnb1^fl/+, Cre⁻ mouse (C, mouse 8740) euthanized at the end of the study (∼400 days). All images were obtained using an Olympus BX41 microscope (Melville, NY) and a 50×/0.9 (oil) or 40×/0.9 objective. Images were processed with Adobe Photoshop (San Jose, CA). Peripheral blood smears, BM smears, and spleen touch preparations were stained with Wright-Giemsa (original magnification ×500), and spleen sections were stained with hematoxylin and eosin (H&E; original magnification ×400).