Letter | Published:

Growth-enhancing protein obtained from cell surface of cultured fibroblasts

Naturevolume 254pages248250 (1975) | Download Citation



NORMAL animal cells do not grow at extremely low cell density under ordinary culture conditions1,2. This property of population dependence on cell proliferation has long been a crucial disadvantage for establishing clonal cultures of animal cells. Feeder layers or conditioned media are therefore used to sustain the growth of single cells in culture. The growth-enhancing material in conditioned media, the conditioning factor, is thought to be a large aggregate of macromolecules of pericellular environment2. This assumption was confirmed by the findings that cultured chick embryo fibroblasts laid down a microexudate carpet on the surface of Petri dishes and that this carpet exerted a growth-enhancing activity on sparsely seeded fibroblasts3,4. Although the microexudate was thought to be composed mainly of glycoproteins, its exact chemical nature has not been known3–5. Here we report the solubilisation and purification of a growth-enhancing protein from the microexudate of cultured chick embryo fibroblasts.

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  1. Biology Division, National Cancer Center Research Institute, Tsukiji 5-chome, Chuo-ku, Tokyo, Japan

    •  & Y. YAOI


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