Determining the mechanical properties and behavior of cells has been studied through a variety of methods including micropipette aspiration, atomic force microscopy (AFM), magnetometry, rheology, and cell indentation. Using the cell poker technique, the force required to indent the cell surface by a glass stylus or the relaxation time of the cell membrane can be determined. This method provides information about both the mechanical properties of adherent cells and the internal cytoskeleton. For example, using the cell poking technique showed that F9 mouse embryonic carcinoma cells were ∼20% more resistant to indentation by the cell poker compared to F9 vinculin-deficient (5.51) cells, which were derived by chemical mutagenization of F9 cells. This was confirmed in viscoelastic measurements using AFM, magnetometry, and rheology.