The biomechanical forces mediated tumor cell invasion. (a) A single unit containing two gel compartments and medium reservoirs with different pressure was headed for forming the interstitial flow to direct tumor cell invasion drive flow. Individual cells tracks can be observed in real time with extended shape.97 Reprinted with permission from U. Haessler et al., Integr. Biol. 4, 401 (2012). Copyright 2012 The Royal Society of Chemistry. (b) Interstitial flow influences direction of tumor cell migration through competing mechanisms. Besides autocrine chemokine signal in the direction of flow, a competing mechanism of tumor cells migrating to the opposite direction of the interstitial flow was found to be associated with FAK Activation.100 Reprinted with permission from W. J. Polacheck et al., Proc. Natl Acad. Sci. U.S.A. 108, 11115 (2011). Copyright 2011 National Academy of Sciences.