Figure 3. Schematic representation of cooperative activation of PI3K and p70S6K by receptor tyrosine kinase and GPCRs, leading to increased ASM proliferation. Agonists (histamine, thromboxane, or thrombin) activating Gq-coupled receptors enhance EGF receptor-activated PI3K activity via release of Gß subunits, resulting in increased activation of downstream targets Akt and p70S6K, which in turn increases ASM proliferation.