To investigate the effect of GCRV infection on the SUMOylation pathway, transcriptional steady state levels of SUMO1, SUMO2 and Ubc9 were determined by real time RT-PCR (Figure 3A, and 3C) during the infection course of GCRV, which was monitored by probing the expression of outer capsid protein VP7 in infected CIK cells (Figure 3D). The gene discussed is SUMO2; the disease is infection.