Fibronectin, one of the typical ligands of integrin, may induce cell attachment and cell spread. On activated integrins binding to the fibronectin, they cluster at the binding site, recruit cytoplasmic proteins to organize focal adhesions and initiate actin stress fibers to rearrange, and finally result in cell adhesion and spreading. Using immunofluorescence to visualize the focal adhesion and actin stress fibers, it was found that after 2 h attachment to fibronectin in serum-free medium, MDA-MB-435 cells were well spread with focal adhesions localized at the periphery of cells and actin stress fibers well organized. For details, see the article by Zhou and colleagues on page 194.