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. Author manuscript; available in PMC: 2012 Apr 1.
Published in final edited form as: Exp Gerontol. 2010 Nov 21;46(4):282–291. doi: 10.1016/j.exger.2010.11.004

Figure 5. Suggested mechanisms for regulation of p70S6k expression and phosphorylation.

Figure 5

Schematic representation of a feed-forward mechanism in which systemic factors regulate p70S6k expression and a feed-back mechanism in which p70S6k phosphorylation and activation is regulated by muscle mass and modulated by muscle load. In aged muscle, maintaining p70S6k phosphorylation despite a decline in amount of p70S6k may require increased (mTOR) kinase activity. The age-related decline in p70S6k may limit the muscles’ ability to respond to stimuli with increased mass.