Figure 1.

VavR double transgenic mice express GFP in hematopoietic cells and RFP in nonhematopoietic cells. (A): On cross-breeding the mTmG mouse with the Vav-Cre, all cells expressing vav 1 (hematopoietic) in the progeny exclude RFP due to cleavage at loxP sites and instead express GFP. Cells not expressing vav 1 (nonhematopoietic) remain RFP+. (B): Flow cytometry of peripheral blood cells is nonfluorescent in wild-type mice and GFP+ in VavR mice. Circulating RFP+ cells are not detected in the peripheral blood of VavR mice. (C): Histological images of spleen, liver, heart, and skin showing distribution of RFP and GFP cells. Nuclei are stained with 4′,6-diami-dino-2-phenylindole. Scale bar =75 μm. (D): Flow cytometry of cells isolated from the heart, spleen, liver, and skin of VavR mice indicates relative proportions of GFP+ and RFP+ cells in each of these organs. (E, F): Immunohistochemistry for CD45 in the spleen (E) and cytokeratin in the skin (F) shows CD45 (purple) colocalizing with GFP and cytokeratin (purple) colocalizing with RFP. White arrows highlight areas of colocalization. Gray arrows illustrate a small population of GFP+/C45− cells in the spleen, indicating that CD45 is not a ubiquitous marker of hematopoietic lineage cells. Gray scale bar =75 μm. White scale bar =150 μm. Abbreviations: GFP, green fluorescent protein; RFP, red fluorescent protein.