PTK2 and cancer: Considering that Fak, or Src, or both, are often deregulated in cancer (including CRC) [6, 14, 36, 37, 39], further studies will be required in order to unravel the determinants that are responsible for the selective engagement of p110α/p85β and p110α/p55γ by Src and Fak, respectively, as reported herein.