Table 2: Human insulin-like growth factor binding proteins.

IGFBPsMass (kDa)Source of purificationRelative binding affinity for IGFs

IGFBP125.0Amniotic fluid, placentaIGFI = IGFII
IGFBP-231.3BRL-3A and MDBK cells, human serumIGFII > IGFI
IGFBP-328.7PlasmaIGFI = IGFII
IGFBP-425.9Human osteosarcomas, prostatic carcinoma, colon carcinoma, and glioblastomaIGFI = IGFII
IGFBP-528.5C2 myoblasts conditioned media, human boneIGFI = IGFII
IGFBP-622.8Cerebrospinal fluid, human serumIGFII > IGFI