HIF1A and neoplasm: Tumor cells seek to adapt to hypoxia by activating a transcription factor called HIF-1 (Hypoxia Inducible Factor 1) via the JNK1 signaling pathway (c-Jun N-terminal kinases, a member of the MAPKs family), which in turn, activates several pro-angiogenic factors, such as VEGF (vascular endothelial growth factor).