SMAD2 and severe acute respiratory syndrome: These comprise the top biological pathways enriched in mitochondrial iron-sulfur cluster biogenesis, metabolism of porphyrins, O2/CO2 exchange in erythrocytes, transcriptional activity of SMAD2/SMAD3:SMAD4 heterotrimer, MHC class II antigen presentation, Rhesus glycoproteins mediate ammonium transport, neddylation, creatine metabolism, potential therapeutics for SARS, oxidative stress induced cellular senescence, and amyloid fibre formation.