  We apply the methods of optimal experimental design to a differential
equation model for epidermal growth factor receptor (EGFR) signaling,
trafficking, and down-regulation. The model incorporates the role of a recently
discovered protein complex made up of the E3 ubiquitin ligase, Cbl, the guanine
exchange factor (GEF), Cool-1 (Beta-Pix), and the Rho family G protein Cdc42.
The complex has been suggested to be important in disrupting receptor
down-regulation. We demonstrate that the model interactions can accurately
reproduce the experimental observations, that they can be used to make
predictions with accompanying uncertainties, and that we can apply ideas of
optimal experimental design to suggest new experiments that reduce the
uncertainty on unmeasurable components of the system.
