| RelA associated inhibitor blocks transcription of human immunodeficiency virus type 1 by inhibiting NF kappaB and Sp 1 actions . ^^^ We found that RAI could also inhibit the DNA binding of Sp 1 and thus inhibit the basal HIV 1 promoter activity . ^^^ We further examined the effects of RAI on Sp 1 and found that RAI colocalizes with Sp 1 in the nucleus and interacts with Sp 1 in vitro and in vivo . ^^^ These findings indicate that RAI acts as an efficient inhibitor of HIV 1 gene expression in which both NF kappaB and Sp 1 play major roles . . ^^^ |