Expression of VEGF by human endothelial cells stimulated with cytokines.

RPAs were performed on RNA samples harvested from resting HUVECs or HUVECs stimulated for 5 hours with increasing concentrations of TNF-α, IL-1α, IFN-γ, or IL-4. Illustrated is the variable low-level expression of VEGF in resting HUVECs with minimal change in expression following cytokine-dependent activation. The expression of VEGF in a renal carcinoma cell line is illustrated as a positive control (Control), and the expression of L32 and GAPDH serves as internal housekeeping gene controls. The expression of IL-1 is also illustrated. All cytokines were assessed for bioactivity in separate studies (not shown). The autoradiographs are representative of 3 experiments with similar results.