A protein growth factor for mammalian cells in culture.

The amino acid and vitamin requirements of mammalian cells in culture have been carefully defined in the studies of Eagle and coworkers (1) who supplemented their medium with 5 per cent dialyzed serum. Knowledge concerning the growth requirements satisfied by the serum is completely lacking. In a preliminary report (2), evidence was presented for the protein nature of one of the serum growth factors. Partially purified from bovine serum, the factor has several marked effects upon mammalian cells in culture (appendix Al’): (a) it causes adherence of cells to a glass surface; (b) only in its presence cells assume a flattened, epithelial-like appearance; and (c) it stimulates cell multiplication. More recently, Fisher et al. (5), working independently with a different cell culture, HeLa Sa, have reported some of these effects. The purpose of this report is to describe the purification and properties of the protein growth factor.