|MadSci Network: Cell Biology|
This is from Molecular Biology of the Cell, third edition,Albert,Bray,Lewis Raff, Roberts and Watson, Garland Pub.Inc.,1994 Protiens called growth factors are responsible for cell division. Cells have receptor sites on their surfaces for a specific growth factor. Once a transmembrane receptor receives its growth factor, the inner part begins a cascade of signals which stimulates gene duplications and cell division. "At the molecular level M phase is initiated by a cascade of protien phophorylations triggered by the activation of the mitosis-inducing kinase MPF,..."
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