The paper develops a model to explain the rheological properties of semiflexible biopolymer networks, such as F-actin, which play a crucial role in the cytoskeleton of cells. The model accounts for the nonclassical rubber elasticity observed in these networks, particularly in the "rubber plateau" regime where the network behaves as an elastic solid. The authors show that the large elastic moduli and strain hardening in actin networks are due to the semiflexible nature of the filaments, where the persistence length is comparable to or larger than the characteristic mesh size of the network. The model predicts that the plateau modulus scales with concentration as \( G' \sim c_A^{11/5} \) for entangled solutions and \( G' \sim c_A^{5/2} \) for densely crosslinked gels. This model provides a framework to understand the viscoelastic behavior of biopolymer networks and makes several testable predictions, including the sensitivity of viscoelasticity to filament length and the differences between entangled solutions and crosslinked gels.The paper develops a model to explain the rheological properties of semiflexible biopolymer networks, such as F-actin, which play a crucial role in the cytoskeleton of cells. The model accounts for the nonclassical rubber elasticity observed in these networks, particularly in the "rubber plateau" regime where the network behaves as an elastic solid. The authors show that the large elastic moduli and strain hardening in actin networks are due to the semiflexible nature of the filaments, where the persistence length is comparable to or larger than the characteristic mesh size of the network. The model predicts that the plateau modulus scales with concentration as \( G' \sim c_A^{11/5} \) for entangled solutions and \( G' \sim c_A^{5/2} \) for densely crosslinked gels. This model provides a framework to understand the viscoelastic behavior of biopolymer networks and makes several testable predictions, including the sensitivity of viscoelasticity to filament length and the differences between entangled solutions and crosslinked gels.