FIGURE 3.

The expression of EGS RNAs in cultured cells. Northern analyses were carried out using nuclear RNA fractions isolated from parental U373MG cells (−, lanes 4 and 8) and a cloned cell line that expressed PR-C125-C (lanes 1 and 5), PR-C125 (lanes 2 and 6), and PR-SER (lanes 3 and 7). Equal amounts of each RNA sample (30 μg) were separated on 2% agarose gels that contained formaldehyde, transferred to nitrocellulose membranes, and hybridized to a ³²P-radiolabeled probe that contained the DNA sequence coding for EGS PR-SER/PR-C125 (lanes 1–4) or H1 RNA (lanes 5–8), the RNA subunit of human RNase P and a nuclear RNA (5). The hybridized products corresponding to the full-length retroviral transcripts (∼6 kb), transcribed from the LTR promoter, are at the top of the gel and are not shown.