FIG. 3.

Effect of HTLV-1 Rex on viral mRNA splicing. The mutant rex genes were cotransfected together with pRRX into 293T cells. The plasmid pRRX is derived from the 3′ half of the HTLV-1 provirus and produces spliced and unspliced HTLV-1 RNAs, whose amounts can be regulated by Rex. Total cellular RNA from transfected cells was separated on a 1% formaldehyde agarose gel, blotted onto a nylon membrane, and hybridized to an intron-specific radioactive probe. Lane 1, pBC12/CMV (unrelated control vector), lane 2, pcRex, lanes 3 to 8, plasmids expressing the indicated Rex mutants. WT, wild type; neg., negative control; GAPDH, glyceraldehyde-3-phosphate dehydrogenase.