As discussed in the main text, the regulation of Rac by Pix/Cool is associated with three different scenarios described by three conditions (and subconditions which are not displayed). When multiple conditioned species are added as part of a condition (as is the case with the first condition of the Pix/Cool module, where the activation states of both PAK and G determine the effects of Pix/Cool on Rac), the user first drags the species of interest into the condition box. Subsequently the user is prompted to select the relationship between the species (boxed in red). The available relationships include “Independent” and “Co-operative”, corresponding to the OR and AND Boolean operators, respectively. The Co-operative relationship is selected for the first condition of the Pix/Cool module. Note that any number of conditioned species can be added as part of a condition, and the selected relationship applies to all conditioned species. Similarly when multiple conditions are specified for a regulation module (as is the case with the Pix/Cool module), the user needs to also specify either an Independent or Co-operative relationship for the conditions (highlighted in blue). In the case of Pix/Cool, there are three independent conditions.