Parameters of RNAi model.

The first set of parameters describes the rate constants of the individual steps in the overall reaction scheme shown in Figure 1. As derived in Materials and Methods, these mechanistic parameters dictate behavior only through their combined effect on two lumped parameters, gamma and beta, which determine the level of knockdown achievable by RNAi and the time required to achieve knockdown. Every mechanistic parameter contributes to at least one of the two lumped parameters. The complete range of behavior of the model can be obtained by varying just γ and β; thus, specific values of the detailed mechanistic parameters are not considered.