HIF1A and neoplasm: Hypoxia not only results in the accumulation of HIF-1α, but also activates the NF-kB transcription factors, PKM2 promotes tumor angiogenesis by regulating HIF-1α through NF-kB activation (35), HIF-1α activates NF-kB, NF-kB controls HIF-1α transcription and that HIF-1α activation may be concurrent with inhibition of NF-kB (36).