Expression of VEGF and VEGF receptors in leukemic cells.

RNA was isolated from leukemic cell lines grown in culture (A) and freshly isolated human leukemia cells (B) as described in “Materials and methods.” RT-PCR was performed on the RNA, using primers corresponding for human VEGF, KDR, NRP-1, and GAPDH cDNA sequences and murine Flk-1 (KDR) and NRP-1 cDNA sequences, as indicated. PCR products were resolved on a 2% agarose gel, stained with ethidium bromide, and visualized under UV light.