[Total protein content of cells as a factor regulating their proliferation].

Proliferation kinetics in stimulated stationary cultures of chick embryo fibroblasts was studied using cytophotometric and autoradiographic methods. Part of 4c cells are blocked at G2 when the culture becomes stationary. A fraction is formed among them which fails to divide in response to proliferation stimulus. Such cells differ from cycling G2 cells by a higher total protein content. Cells with an elevated total protein content are found among 2c cells too, and these also fail to synthesize DNA in response to stimulation to proliferation. It is concluded that the quantity of protein accumulated in the cytoplasm may be one of the factors controlling cell proliferation.