FIGURE 1.

PI3K/PTEN–mTOR pathway. mTOR is activated by signaling through the PI3K–Akt pathway, regulating cell growth and proliferation. PTEN, TSC1, and TSC2 act as negative regulators of the mTOR pathway, and removal leads to hyperactivation of mTOR. mTOR complex 1 (mTORC1) signaling requires activation of the adaptor protein raptor, and mTOR complex 2 (mTORC2), which is largely insensitive to acute rapamycin treatment, requires activation of the rictor protein. Although regulation of mTORC2 is less clearly defined, it has been linked to cytoskeleton organization.