Fig. 7. Extracellular matrix components function effectively to modulate Shh diffusivity. (A) Gli1 intracellular concentration at t=83 hours is shown at various levels of initial HSPG extracellular concentration. (B) The Gli1 protein interface position at t=83 hours is shown at various levels of HSPG extracellular concentration. Simulation initial conditions and parameters are the same as those listed in Fig. 2; however, HSPG mechanism equations and parameters were added (see Fig. S4 in the supplementary material).