PlGF-1 is an angiogenic factor that belongs to the cysteine-knot superfamily of growth factors. PlGF-1 is expressed in placental tissues, the colon, and mammary carcinomas. It signals through the VEGFR-1/FLT1 receptor, and stimulates endothelial cell proliferation and migration. Recombinant Rat PlGF-1 is a 30.3 kDa disulfide-linked homodimeric protein of two 135 amino acid polypeptide chains.