Flow cytometric analysis of the differentiation of ES cells into EC lineage. (A) CCE ES cells were cultured on type IV collagen-coated dishes in the absence of leukemia inhibitory factor. After 4 days for ES cell differentiation, Flk-1⁺E-cadherin⁻ cells were sorted and recultured under the same conditions. (B) The expression of Flk-1 and VE-cadherin on sorted Flk-1⁺ cells during 3 days in culture. (C) The expression of VE-cadherin and PECAM-1 or CD34 on the Flk-1⁺population during 3 days in culture. (D) The expression of Flk-1 and PECAM-1 or CD34 on the VE-cadherin⁺ population during 3 days in culture.