Sam68ΔC selectively suppresses expression of mRNAs exported by the Rev/RRE complex. a) An illustration of the two HIV-1 Gag expression constructs used: Gag-RRE and Gag-CTE. b) 293T cells were transfected with either Gag-RRE or Gag-CTE plasmids in the absence (-) or presence (+) of expression vectors for Rev and Sam68ΔC. Forty-eight hours post-transfection, cell lysates were prepared, fractionated on SDS-PAGE gels and blotted. Blots were probed to detect levels of Gag (p55 and p24, α-Gag), Sam68ΔC (α-myc), Rev (α-Rev) and tubulin (α-tubulin). c) Quantitation of Gag expression over multiple assays, results being normalized to tubulin levels. Asterisks denote samples determined to have significantly different levels of p24 expression from that seen with Gag-RRE and Rev at a p < 0.01.