All chemicals were purchased from Sigma-Aldrich (St. Louis, MO) and Fisher Scientific (Pittsburgh, PA), unless otherwise indicated. The following primary antibodies were used: rabbit anti-β-actin (Chemicon, Temecula, CA); mouse anti-histone 2B (Cell Signaling Technologies, Beverly, MA); rabbit anti-RhoA and rabbit anti-FAK (Santa Cruz Biotechnologies, Santa Cruz, CA); mouse anti-FAK, mouse anti-paxillin, and rabbit anti-phosphotyrosine (BD Transduction Laboratories, Lexington, KY); rabbit anti-Tyr(P)31 paxillin, rabbit anti-Tyr(P)418 Src, rabbit anti-Src, and rabbit anti-Tyr(P)397 FAK (Biosource International, Camarillo, CA). The following secondary antibodies were used: goat anti-rabbit-AlexaFluor 594, chicken anti-mouse-AlexaFluor 488, goat anti-rabbit-AlexaFluor 488, chicken anti-mouse-AlexaFluor 594, goat anti-rabbit IgG-FITC, goat anti-mouse IgG-Cy3, and chicken anti-mouse-FITC (Molecular Probes, Eugene, OR). Donkey anti-rabbit IgG (Cell Signaling Technologies) or goat anti-mouse IgG (Pierce Biochemicals, Rockford, IL) conjugated to HRP was used for immunoblot analysis with extended-duration substrate (Super Signal West Dura; Pierce Biochemicals) and the ECL (GE Healthcare, Piscataway, NJ) detection system. Other reagents included: Tβ4 (the kind gift of Hynda K. Kleinman, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD); antifade mounting medium (Vectashield; Vector Laboratories, Burlingame, CA); a protein assay kit (DC; Bio-Rad, Hercules, CA); and rhodamine-phalloidin (Molecular Probes).