FOS and viral infectious disease: Genes in cluster 0 (blue) included JUN, JUNB, FOS, FOSB and ATF, which together form the AP-1 transcription factor, and the MAPK signaling genes DUSP1 and DUSP2, both of which control cellular differentiation and proliferation during viral infection (73) along with EGR2, which is also expressed by cluster 0 (74, 75).