Figure 5. Schematic of the proposed signalling mechanisms involved in the activation of mTOR by growth factors and eccentric contraction.

Growth factors such as insulin activate mTOR through a PI3K-dependent mechanism. Eccentric contractions activate mTOR through a PI3K-independent mechanism involving PLD and PA. Eccentric contractions also activate signalling through p38 and JNK. Activation of signalling through mTOR, p38 and JNK might be elicited through a common mechanotransduction mechanism, but the activation of signalling through p38 and JNK does not appear to be involved in the activation of mTOR.