Figure 3.

Botulinum C3 toxin and the H-7 serine/threonine kinase inhibitor induce alterations in cell morphology, focal adhesions, and the actin cytoskeleton similar to those induced by caldesmon transfection. (A and B) Control culture; (C and D) cells treated with C3 toxin; (E and F) cells treated with H-7. (A, C, and E) Staining with anti-phosphotyrosine antibody; (B, D, and F) staining with FITC-phalloidin of the same fields, respectively. Note significant decrease in the size of focal adhesions and disruption of actin stress fibers in cells treated with inhibitors. Note also that C3 toxin- and H-7-treated cells exhibit elongated cell processes (D and F).