Figure 3. EGS RNA expression in cultured cells. Northern analyses were performed using nuclear RNA fractions isolated from parental U373MG cells (-, lanes 4 and 8) and a cloned cell line that expressed CSP-SER (lanes 3 and 7), CSP-C321 (lanes 2 and 6), and CSP-C321-C (lanes 1 and 5). 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 CSP-SER/CSP-C321 (lanes 1–4) or H1 RNA (lanes 5–8), the RNA subunit of human RNase P and a nuclear RNA.¹² The hybridized products corresponding to the full-length retroviral transcripts (~6kb), transcribed from the LTR promoter, are at the top of the gel and are not shown.