Mammalian cell growth proteins. I. Growth stimulation of fetuin.

This is the authors' abstract. We don't add key points for this paper.

The relationship between various materials which may be present in a fetuin fraction of fetal calf serum and their biological activity observed for the fraction as a whole is clarified. Addition of fetuin produced maximum reproduction of single bovine ovary cells in synthetic F12 medium whereas crystalline albumin had little effect and crystalline alcohol-precipitated albumin had no effect or inhibited growth. Fetuin antibody precipitates specifically with fetuin and destroys all growth of bovine ovary cells; growth inhibiton is reversed by fetuin addition. Therefore the action of fetuin on cell division is specific and different from that of albumin which does not reverse inhibition upon addition. In gel electrophoresis the standard fetuin preparation exhibits 1 major component and 6 or 7 minor ones. Evidence suggests that the principle component of the fetuin fraction contains the bulk of its biological activity. Many different mammalian cells responded to bovine fetuin and several different adult and fetal mammalian sera were similarly deprived of their cell stimulatory growth power by treatment with antifetuin gamma globulin. Therefore the factor studied here appears to be of general importance in mammalian cell growth.