Fig. 1

Osteoblast subpopulations in the tumor microenvironment in vivo. a Athymic nude mice were injected via intratibial injection with an admix of MDA-MB-231GFP/Luc2 human breast cancer cells plus osteoblasts or b PBS. Eight weeks later, mice were euthanized and their tibia harvested. Sections were stained for alpha-smooth muscle actin, osteopontin, green fluorescent protein, and DAPI via immunofluorescence. Inset: Orange arrows show alpha-smooth muscle actin-positive, osteopontin-positive osteoblasts. White arrows show alpha-smooth muscle actin low, osteopontin positive "educated" osteoblasts. a T, tumor; Bo, bone. b Non-cancer bearing bone (control). TB, trabecular bone; BM, bone marrow