CD28 and rheumatoid arthritis: Examples include a module associated with rheumatoid arthritis that comprises the B7:CD28 costimulatory pathway required for T cell activation, which is blocked by an approved drug (Fig. 6a); a module associated with inflammatory bowel disease corresponding to cytokine signaling pathways mediated by Janus kinases (JAKs), which are therapeutic targets (Fig. 6b) and a module associated with myocardial infarction that includes the NO/cGMP signaling cascade, which plays a key role in cardiovascular pathophysiology and therapeutics (Fig. 6c).