Role of tensile stress in actin gels and a symmetry-breaking instability K. Sekimoto, J. Prost, F. Jülicher, H. Boukellal and A. Bernheim-Grosswasser Eur. Phys. J. E, 13 3 (2004) 247-259 Published online: 23 March 2004 DOI: 10.1140/epje/i2003-10073-y