A mathematical model of phototransduction fairly reproduces effects of forskolin on flash photoresponse. “Cell 1” and “Cell 2” refer to the cells’ numbers in Tables 1 and S2. Noisy traces, experimental responses; smooth traces, model. For Cell 1, each trace is an average of eight responses (normal solution) or four responses (forskolin solution) to flashes of 0.94 photons · µm⁻². For Cell 2, each trace is an average of eight responses (normal solution) or six responses (forskolin solution) to flashes of 0.37 photons · µm⁻². For the description of the model, see Materials and methods. Parameters that were modified to imitate forskolin effects are summarized in Table 1. Coefficient of correlation between experimental recordings and model curves, r² > 0.995.