To determine the pathways that may contribute to the progression of sarcoidosis, we mapped the differentially expressed proteins between the progressive and non-progressive cases to canonical pathways in IPA (Table 8); these include aryl hydrocarbon receptor signaling, clathrin-mediated endocytic signaling, glutathione redox reaction, glutathione-mediated detoxification, antigen presentation pathway, phagosome formation, CD28 signaling in T-helper cells, CDC-42 signaling, RhoA signaling and PFKFB4 signaling pathway (Fig. 5). This evidence concerns the gene CD28 and sarcoidosis.