GO:0036323

Any series of molecular signals initiated by the binding of an extracellular ligand to a vascular endothelial growth factor receptor-1 (VEGFR-1) located on the surface of the receiving cell, and ending with regulation of a downstream cellular process, e.g. transcription. [GOC:bf, GOC:uh, PR:000007563, Wikipedia:FLT1, Wikipedia:VEGF_receptors]