SP1 and infection: At the later stage of infection (48 h p.i.), the binding activities of NF-κB p50 and Sp1 with the il10 promoter in PCV2-Rep1-infected cells were lower than that in the PCV2-infected cells, whereas the binding activities of NF-κB p50 and Sp1 with the il10 promoter in PCV1-Rep2-infected cells were beginning to be detected and appeared to be higher than that in PCV1-infected cells (Figure 6A–D).