PTPRC and neoplasm: Our immunohistochemistry (IHC) staining further revealed that the tumor cells in the adrenal glands of Nfkb1-/-/Tax+ mice were positive for the immune cell marker CD45 and the macrophage marker F4/80 (Fig 2A), suggesting that macrophages were the cells of origin of the adrenal medullary tumors in the Nfkb1-/-/Tax+ mice.