Signaling pathway leading to the activation of paxillin. (A) Effects of the knockdown of Lyn on the phosphorylation levels of p130Cas, FAK, and paxillin in GD3/GD2+ and control cells were analyzed by immunoblotting. (B) Immunoprecipitation (IP)/immunoblotting (IB) was carried out to examine the co‐immunoprecipitation of FAK, p130Cas (Cas), or Lyn with paxillin (Pax) using anti‐paxillin and individual antibodies (Lyn, FAK, and p130Cas) in vector control cells and GD3/GD2+ transfectant cells. (C) Effects of the double knockdown of Lyn and FAK on the phosphorylation levels of p130Cas, FAK, and paxillin in GD3/GD2+ cells were analyzed by IB. (D) Effects of the knockdown of FAK on the phosphorylation levels of Lyn were examined in G19. (E) Relative intensity of bands in (A,C) were measured using NIH Image 1.61. The results shown are averages ± SD. **P < 0.01. (F) Intensities of adhesion and spreading of GD3/GD2+ cells treated with anti‐Lyn/FAK, or anti‐Lyn or anti‐FAK siRNAs against Lyn and FAK, were analyzed by real‐time cell electronic sensing.