ABSTRACT Cancer cell adhesion is traditionally viewed as random, occurring if the cell's receptors match the substrate. Cancer cells are subjected to pressure and shear during growth against a constraining stroma, surgical manipulation, and passage through the venous and lymphatic system. Cells shed into a cavity such as the abdomen postoperatively also experience increased pressure from postoperative edema. Increased extracellular pressure stimulates integrin‐medi‐ated cancer cell adhesion via FAK and Src. PI 3‐kinase (PI3K) inhibitors (LY294002 or wortmannin), Akt inhibitors, or Aktl siRNA blocked adhesion stimulated by 15 mmHg pressure in SW620 or primary human malignant colonocytes. Pressure activated PI3K, tyrosine‐phosphorylated and membrane‐translocated the p85 subunit, and phosphorylated Akt. PI3K inhibitor (LY294002) prevented pressure‐stimulated Akt Ser473 and FAK Tyr397, but not FAK576 or Src416 phosphor‐ylation. PP2 inhibited PI3K activity and Akt phosphor‐ylation. FAK siRNA did not affect pressure‐induced PI3K activation but blocked Akt phosphorylation. Pressure also stimulated FAK or FAKY397F mutant translocation to the membrane. Akt inhibitor IV blocked pressure‐induced Akt and FAK translocation. Pressure activated Src‐ and PI3K‐dependently induced p85 interaction with FAK, and FAK with βl integrin. These results delineate a novel force‐activated inside‐out Src/ PI3K/FAK/Akt pathway by which cancer cells regulate their own adhesion. These signals may be potential targets for inhibition of metastatic adhesion.—Thamil‐selvan V., Craig D. H., Basson M. D. FAK association with multiple signal proteins mediates pressure‐induced colon cancer cell adhesion via a Src‐dependent PI3K/Akt pathway. FASEB J. 21, 1730–1741 (2007)