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Updated: Aug 16, 2026

Grafting of Beads into Developing Chicken Embryo Limbs to Identify Signal Transduction Pathways Affecting Gene Expression
Published on: January 17, 2016
Many growth factors may not be growth factors
1Department of Pathology, University of Washington, Seattle 98195.
Abstract:
Both organ growth and tumor growth are dependent upon a biased ratio of cell births to cell deaths; this ratio is independent of the frequency of mitosis. Thus, so-called growth factors that affect only the frequency of mitosis are not really growth factors. I shall advance two hypotheses: that the normal adult ratio of cell births to cell deaths is maintained by the activity of a factor or factors produced by the stem cells; and that the differentiating cells, as well as the stem cells, produce a different factor that limits the frequency of mitosis.
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