Expression of VEGF/VPF receptors in PEL cells detected by RT-PCR. cDNAs from HUVECs, PEL cells (BC-1, BCP-1, and BCBL-1), and skin fibroblast (Hs68) cells were subjected to PCR amplification for Flt-1 and Flk-1/KDR (498- and 709-bp products, respectively). The quality of RNA was confirmed by parallel RT-PCR amplification for GAPDH. MWM, molecular weight marker.