sentences:  However, when total cellular RNA was analyzed, "env" RNA totals were not significantly difference in the presence and absence of "rev" coexpression.It was found that without "rev" expression, there was a marked increase in nuclear "env" RNA, which suggests that "rev" plays an important role in the nuclear export of "env" mRNA.The role of "rev" was further elucidated when it was found that Rev acts in trans to target a specific sequence present in the "env" gene of HIV-1 to initiate export of incompletely spliced HIV-1 RNA from the nucleus.