Fig. 4.

Upstream control of AKT activation. PI3K inhibition (A) blocked AKT activation (n = 9, *P < 0.001), but neither Src inhibition (B, n = 6, *P < 0.04) nor Src reduction by siRNA (C) prevented strain-induced AKT activation (n = 10, *P < 0.05) in Caco-2 cells. However, reducing focal adhesion kinase (FAK) or Rac1 by siRNA prevented strain-induced phosphorylation of AKT (D, n = 5, *P < 0.05) and PI3K p85 subunit (E, n = 7, *P < 0.001). siRNA transfection achieved ∼60–80% knockdown as shown by immunoblot (F).