This phenomenon is regulated by the hydrodynamic shear rate in leukocyte–tumor cells under flow conditions.41 Furthermore, it was recently reported that a stiff ECM promotes epithelial–mesenchymal transition and tumor metastasis by induction of TWIST1 nuclear localization.42 These studies suggest that a stiff substrate promotes cancer progression by affecting the multistep processes of tumorigenesis and metastasis in various cancer cell types. The gene discussed is TWIST1; the disease is neoplasm.