Figure 3.

The expression of M1GS ribozymes in human cells. Northern analyses were carried out with RNA isolated from parental U373MG cells (−, lane 4) and two sets of cloned cell lines that expressed M1-TK (lanes 1 and 5), M1-IE (lanes 2 and 6), and C-IE (lanes 3 and 7) ribozymes. Equal amounts of each RNA sample (30 μg) were separated on 2.5% agarose gels that contained formaldehyde, transferred to a nitrocellulose membrane, and hybridized to a ³²P-radiolabeled probe that contained the DNA sequence coding for M1 RNA. The hybridized products corresponding to the full-length retroviral transcripts (≈6 kb), transcribed from the long terminal repeat promoter, are at the top of the gel and are not shown.