STAT3 and neoplasm: Whereas STAT3 O-GlcNAcylation promotes Tyr705 phosphorylation, it inhibits Ser727 phosphorylation (59, 60), thereby enhancing metastasis by regulating STAT3 signaling and target gene transcription.Nuclear factor erythroid 2-related factor 2 (Nrf2) is another transcription factor, the activation of which plays a critical role in sustained angiogenesis, tumor invasion and metastasis (79).