Fig. 6. Characterization of SD′ gene product. (A) Western blot analysis of cellular SD′ gene products. The p50 protein was detected with an anti-Pol antibody in infected NIH3T3 cells transfected with p57cDNASD′ (left panel). The right panel shows western blot analysis by using an anti-IN antibody. NIH3T3 cells (lane 1) were transfected with empty GFP vector (lane 2), p57SD′/GFP (lane 3) and p57cDNASD′ (lane 4). Infected NIH3T3 cells were transfected with p57cDNASD′ (lane 5). (B) Structure of p50 and p60 polyproteins encoded by SD′ mRNA.