Qp contains potential STAT-binding sites. (A) The relative locations on the EBV genome of the Qp, Cp, and BamHI-W promoter (Wp) latency promoters and the ORF (BKRF1) encoding EBNA-1 are illustrated. The DNA sequence from −100 to +36 that was included in the Qp-CAT reporter is shown. The position of the IRF-binding site (broken line), two potential STAT-binding sites (underlined), and RNA start site (arrow) are indicated. The nucleotides in lowercase show the mutations introduced into QpSTATm1–CAT and QpSTATm2–CAT. (B) Comparison of STAT DNA-binding sequences with the potential Qp STAT sequences (38). (C) Activation of Qp-CAT by JAK-1. HeLa cells were transfected with a control STAT–CAT reporter or Qp-CAT reporter. As indicated, cells were also cotransfected with JAK-1 or JAK-1 plus STAT-1 or treated with IL-6. The results shown are an average of two experiments with the standard deviation indicated.