We have recently suggested that Grp1, EFA6B and EFA6D, of 7 Arf6-specific GEFs so far identified in mammalian cells, spatiotemporally activate Arf6 in the HGF-stimulated vascular endothelial cell to regulate β1 integrin recycling that is the critical cellular event for the HGF-induced tumor angiogenesis11. Here, HGF is linked to neoplasm.