We use laser tweezers to study plasma membrane mechanics on outer hair and human embryonic kidney cells. Our experiments involve: (1) recording force and displacement profiles while pulling plasma membrane tethers using optically-trapped fluorescent microspheres; (2) combined epifluorescence and transillumination microscopy for spectral separation of the cell and fluorescent microsphere images; (3) modulation of plasma membrane mechanical properties with amphipathic pharmacological agents (salicylate), extracellular osmolarity, and transfected membrane proteins (prestin). The data obtained from experimental studies is processed to be used in mechanical models