MAP2K6 and IRF7 induce Tat-mediated cellular gene modulation via the p38-STAT1 pathway. mRNA levels of ISGs in KG-iDC (A) and type I IFNR2-deficient 5UA cells (B) transfected with MAP2K6 and IRF7 siRNAs and infected with Ad-Tat_SF2/Ad-tTA or Ad-tTA alone. Results are normalized to actin and reported as fold induction relative to Ad-tTA–infected cells treated with nonspecific (ns) siRNA. mRNA levels of selected ISGs in (C) STAT1-deficient U3A cells, (D) U3A-R cells (U3A reconstituted with STAT1) infected with Ad-Tat _SF2/Ad-tTA or Ad-tTA alone and transfected with MAP2K6 siRNA, and (E) STAT2-deficient U6A cells treated with ns siRNA or siMAP2K6 RNA and infected with Ad-Tat_SF2/tTA or Ad-tTA alone.