Figure 1.

The PI3K/Akt/mTOR pathway. Following growth factors stimulation and subsequent activation of RTKs and GPCRs, PI3K is recruited to the plasma membrane directly or through adaptor protein and phosphorylated PIP2 producing PIP3, which recruits and activates PDK1. Akt activation is mediated by PDK1 on T308 and by mTORC2 complex on S473. Akt controls the activity of mTORC1 inactivating the GTPase activity of the TSC1/TSC2 complex toward the mTORC1 activator Rheb. mTORC1 activation induces protein synthesis via p70S6K and 4EBP1. The tumor suppressor gene PTEN acts on this pathway antagonizing the PI3K action on PIP3.