PI3K–AKT–mTOR Pathway

    • Phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) pathway is a key regulator of normal cellular processes. Aberrant activation of this pathway leads to survival and proliferation of tumor cells.
    • PI3K activation leads to phosphorylation and activation of AKT, which in turn can activate mTOR. The pathway can be suppressed by TSC1 (Hamartin), TSC2 (Tuberin), and phosphatidylinositol-3,4,5-triphosphate 3-phosphatase (PTEN).
    • PI3Ks are divided into three classes according to structural characteristics and substrate specificity:
      • Class IA PI3Ks: heterodimers consisting of a p110 catalytic subunit (isoforms p110α, p110β, and p110δ encoded by egulatory subunit (isoforms p85α [and slice variants p55α and p50α] encoded by PIK3R1, p85β encoded by PIK3R2, and p85γ encoded by PIK3R3)
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