Similar transforming growth factors (TGFs) produced by cells transformed by different isolates of feline sarcoma virus.

Fisher rat embryo cells transformed by each of three independent isolates of feline sarcoma virus (FeSV) are shown to release transforming growth factors (TGFs) into cell culture medium. These acid- and heat-stable peptides compete for binding to, and stimulate phosphorylation of, EGF membrane receptors and promote anchorage-independent cell growth. Cells transformed by the Gardner and Synder-Theilen strains of FeSV produce high titers of TGF (60-200 ng eq EGF/liter) while cells transformed by McDonough FeSV produce TGF at only low levels (less than 10 ng eq EGF/liter). Growth factors produced by cells transformed by each of the three FeSV isolates functionally and biochemically resemble each other, mouse sarcoma growth factor (SGF), and TGFs produced by human tumor cells.