Two-step tension tests with reloads along different directions are performed on rolled Mg alloy sheet at room temperature. The experimental yield stress at reloading is systematically lower than before unloading. Such a behavior is captured by a microstructure-based hardening model accounting for dislocation reversibility and back-stress. This formulation, embedded in the Visco-Plastic Self-Consistent (VPSC) model, links the dislocation density evolution throughout the deformation with hardening. The predicted results agree well with the experimental data in terms of flow stress response and texture evolution. The effects of texture anisotropy and back-stress on the mechanical response during the strain path change are discussed.