Actin Cytoskeletal Structure in Migrating Cells -- Actin Cytoskeleton Generates Mechanical Forces for Cell Migration -- Multi-scale Mechanochemical Interactions between Cell Membrane and Actin Filaments -- Actin Network Flow and Turnover are coupled in Migrating Cells -- Mechanical Strain is involved in Actin Network Reorganization -- Actin Network Dynamics is Regulated by Actomyosin Interactions -- Biophysical Interactions between Cells and Extracellular Matrix -- Cell Migration in Engineered Micro-/Nano-environments with Controlled Physical Properties -- Engineered Biomaterial for Cell Manipulation.