Before revision:  Here, we present an application of the method of sinusoidal-input describing function for the analysis of such a system. Using this technique, we approximate the input-output response of a simple biomolecular signaling system both computationally and analytically.
After revision:  Here, we present an application of the method of describing functions to represent the input-output response of a simple biomolecular signaling system both computationally and analytically.