SOCS3 and infection: In IC-21 cells immunofluorescently labeled with anti-SOCS1 or anti-SOCS3 antibodies, treatment with medium or UVi-MCMV resulted in basal to moderate SOCS1 or SOCS3 protein expression, while SG-MCMV infection (MOI = 3 PFU/cell, 3 hpi) caused robust stimulation of these proteins (Fig 4), found mostly in the cytoplasm.