Fms-like tyrosine kinase-1 (flt-1) was shown to be a VEGF receptor by Ferrara et al. in 1992.[10] The kinase insert domain receptor (KDR) was shown to be a VEGF receptor by Terman et al. in 1992 as well.[11] In 1998, neuropilin 1 and neuropilin 2 were shown to act as VEGF receptors.[12]