Signal Transduction Pathways in Breast Cancer: The Important Role of PI3K/Akt/mTOR

Figure 2

Mechanism of action of PI3K and PTEN. RTK receptors are activated, phosphorylating themselves and other series of adapter proteins, such as IRS-1. In this case, the regulatory subunit p85 binds to these residues and releases the catalytic subunit p110α, which adds a phosphate to PIP2 and transforms it into PIP3, which will subsequently activate Akt. PTEN prevents this activation by dephosphorylating PIP3. The loss of function of this gene, represented in red, or activating PI3KCA mutations, shown in green, can overactivate this route, favouring the development of cancer.