HIF1A and colorectal carcinoma: Multiple signaling molecules and pathways such as hypoxia-inducible factor 1α (HIF1α), vascular endothelial growth factor (VEGF)/vascular endothelial growth factor receptor (VEGFR), phosphoinositide 3-kinases (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR), transforming growth factor β (TGFβ), extracellular-signal-regulated kinase (ERK) and WNT/β-catenin contribute to CRC angiogenesis.