IGF1-induced proliferation was a function of steady-state levels of IGF1-IGF1R complexes. A, Diagram of interactions included in the model. B, The computationally-determined concentration of steady-state levels of IGF1-IGF1R complexes exhibited a linear relationship with the experimentally-observed increase in proliferation between IGF1-treated OVCAR5 and vehicle controls. Theoretical saturation of IGF1R is represented by an *. C, Model predictions and experimental results of the effect of IGFBPs on OVCAR5 proliferation in response to IGF1 treatment. The steady-state model predicted that the presence of IGFBPs in the cell culture media would reduce steady-state levels of IGF1-IGF1R complexes and result in decreased cell proliferation. Experimental tests confirmed both the qualitative and quantitative extent of this IGFBP effect. *indicates significant difference (p < 0.05) from IGFBP-negative condition, n = 3 per treatment.