Hepatic levels of CDK8 and CycC proteins are down regulated during aging.

<p>C57BL/6J mice were maintained on a normal chow diet and at the ages indicated were fasted for 16 h and liver extracts prepared. <b>A-B</b>) Representative immunoblots showing the levels of indicated proteins in livers of mice with indicated ages, as detected by immunoblotting. β-tubulin or TBP served as the invariant controls. Each lane is from the equal pooling of liver extracts from six mice. The relative protein levels of CDK8 (<b>C</b>), CycC (<b>D</b>) and phosphorylated S6K1 (<b>E</b>) were further analyzed by densitometry. *p<0.05, **p<0.01 and ***p<0.001 vs. control (n = 6).