The present invention relates to cDNA encoding a soluble neuropilin protein (sNP) which is isolated from neuropilin (NP) producing cells or is recombinantly engineered from NP-encoding DNA. NP-1 and NP-2 are preferred NPs but any neuropilin or VEGF receptor (VEGFR), where the constituents share at least about 85% homology with either of the above VEGF.sub.165R/NP-1 and NP-2. More preferably, such constituent shares at least 90% homology. Still more preferably, each constituent shares at least 95% homology.