Fig. 1. (a) Detection of indentation based on AFM measurements. Cancer cells show higher ability to deform (i.e., greater indentation depth); therefore, cantilever deflection is reduced. Following cetuximab treatment, the indentation depth is reduced because of increased cell stiffness, resulting in increased deflection of the probing cantilever. (b) Force-versus-indentation curves in A549 cells following cetuximab treatment (red), control (green), and with EGF treatment (blue). Lines denote a smooth fit to experimental data (dots).