Fibroblast growth factor-4, also known as FGF-K or K-FGF (Kaposis sarcoma- associated FGF), is a 25kD secreted, heparin-binding member of the FGF family. The mouse FGF-4 cDNA encodes 202aa with a 29aa signal sequence and a 173aa mature protein with an FGF homology domain that contains a heparin binding region near the C-term- inus. Mature mouse FGF-4 shares 87%, 90%, 87% and 85% aa identity with human, rat, canine and bovine FGF-4, respectively. Expression of FGF-4 and its receptors, FGF R1c, 2c, 3c and 4, is spatially and temporally regulated during embryonic development. Its expression in the trophoblast inner cell mass pro- motes expression of FGF R2, and is required for maintenance of the troph- ectoderm and primitive endoderm. Later in development, FGF-4 works together with FGF-8 to mediate the activities of the apical ectodermal ridge, which direct the outgrowth and patterning of verte- brate limbs. FGF-4 is proposed to play a physiologically relevant role in human embryonic stem cell self- renewal. It promotes stem cell proliferation, but may also aid differentiation depending on context and concentration, and is often included in embryonic stem cell media in vitro. A C-terminally truncated 15kD isoform that opposes full-length FGF-4 and promotes differentiation is endogenously expressed in human embryonic stem cells. FGF-4 is mitog- enic for fibroblasts and endothelial cells in vitro and has autocrine transforming potential. Source: Recombinant corresponding to aa30-202 of mouse FGF-4, expressed in E.coli (NP_034332). SDS-PAGE: 19kD, reducing conditions Activity: Measured in a cell proliferation assay using NR6R-3T3 mouse fibroblasts. The ED50 for this effect is typically 0.75-3.75ng/ml. Storage and Stability: Lyophilized powder may be stored at -20C. Stable for 12 months at -20C. Reconstitute with sterile PBS, 0.1% BSA or HSA. Aliquot to avoid repeated freezing and thawing. Store at -20C. Reconstituted product is stable for 6 months at -20C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.
