Next we demonstrated that CIITA increased Gag processing through the viral protease and evaluated whether this enhancement was a consequence of CIITA-mediated transcriptional activation. The CIITA L1035P mutant, which fails to translocate to the nucleus [58] , demonstrated increased Gag processing and virus release compared to vector-only control, suggesting a cytoplasmic role for CIITA in the later stages of the HIV infection cycle. This does not preclude the possibility that an undetectable level of CIITA L1035P might translocate to the nucleus. However, no L1035P was detected in the nucleus after a 24 hour treatment with the nuclear export inhibitor, leptomycin B [58] . Further, the predominantly cytoplasmic GTP-binding CIITA mutants, GTP2 and GTP3, had a similar increase in infectious virus release versus vector-only expressing cells.