Fig. 4. Shh binding to Hedgehog-interacting-protein (Hip) shifts pattern ventrally. The Gli1 protein interface position at t=83 hours is shown at various levels of (A) initial Hip surface concentration and (B) maximal Gli1-induced rate of Hip synthesis, k_Hipmax. Simulation initial conditions and parameters are the same as those listed in Fig. 2; however, Hip mechanism equations and parameters were added (see Fig. S4 in the supplementary material).