Placenta growth factor (PlGF) is a member of the vascular endothelial growth factor family of cytokines that control vascular and lymphatic endothelium development. It has been implicated in promoting angiogenesis in pathological conditions via signaling to vascular endothelial growth factor receptor-1. PlGF expression is induced by hypoxia and proinflammatory stimuli. Metal responsive transcription factor 1 (MTF-1) was shown to take part in the hypoxic induction of PlGF in Ras-transformed mouse embryonic fibroblasts. Here we report that PlGF expression is also controlled by NF-kappaB. We identified several putative binding sites for NF-kappaB in the PlGF promoter/enhancer region by sequence analyses, and show binding and transcriptional activity of NF-kappaB p65 at these sites. Expression of NF-kappaB p65 from a plasmid vector in HEK293 cells caused a substantial increase of PlGF transcript levels. Furthermore, we found that hypoxic conditions induce nuclear translocation and interaction of MTF-1 and NF-kappaB p65 proteins, suggesting a role for this complex in hypoxia-induced transcription of PlGF.