The cell surface of animal cells is a composite interface with several layers, the plasma membrane, the actomyosin cortex and a protein layer that binds them together. Biochemically and mechanically each of these layers differs.My group is taking an engineering-inspired approach, combined with traditional cell biology methods, to quantitatively measure and predict how the various mechanical layers at the surface of animal cells govern function. Together, our work identifies membrane-to-cortex attachment as a critical mechanotransducer in cells, and membrane-to-cortex distance as a key geometrical parameter that regulates protein activity at the cell surface.