Here, VEGF expression inhibition results in the up-regulation of other angiogenic factors such as basic fibroblast growth factor (bFGF) and angiopoietin (Ang-1), whereas endothelial cells under hypoxic conditions exhibit the opposite pattern of VEGF up-regulation. This mechanism may help to explain why a combination approach may be more successful in preventing the recurrence of neovascularization in ROP than the selective suppression of a single growth factor. The gene discussed is FGF2; the disease is retinopathy of prematurity.