Figure 4: Different modelling tools a) Building a model with the software tool Athena. Top panel illustrates a reversible reaction between folate and tetrahydrofolate. Bottom panel shows a simulation of these two species. b) Graphical representation of the Nijhout et al model (2004) after importation of the SBML code to Cell Designer C) Representation and simulation of the Nijhout model in Copasi d) Graphical representation of the Nijhout et al. [59] model with the modelling tool JDesigner.