EGF and squamous cell carcinoma: In the first, A431 human epidermoid carcinoma cells were stimulated by EGF, triggering H2O2 intracellular production that lead to PTP1B oxidation and inhibition (Figures 6A,B), while in the second experiment, rat-1 cells were stimulated with PDGF inducing SHP-2 oxidation (Figures 6C,D).