Notch is upregulated in VE-cadherin–expressing cells that egressed the bone marrow. (A-C) FACS sorting results are shown for 3 populations of cells from (A) the bone marrow, (B) the blood, and (C) the tumor of the CIVE mice after tamoxifen induction. (D) Shown is a schematic overview of the different stages of the EYFP⁺ cells. (E-H) From the bone marrow, a population of EYFP⁻/PECAM⁺ and a population of EYFP⁺/PECAM⁺ were sorted. From the blood, the EYFP⁺/PECAM⁺ population was sorted. RT-PCR was performed for levels of different proteins in the 4 populations: (E) BM EYFP⁻/PECAM⁺, (F) BM EYFP⁺/PECAM⁺, (G) blood EYFP⁺/PECAM⁺, and (H) tumor PECAM+/EYFP+, showing the endothelial markers (gray), Notch1/Dll4 (red), and the macrophage markers (black). eNOS, endothelial nitric oxide synthase; iNOS, inducible nitric oxide synthase; ICAM, intercellular adhesion molecule; mRNA, messenger RNA; VCAM, vascular cell adhesion molecule.