Comparison of the level of expression of the ^Aγ* gene in cells containing a tandem array of rHS32^Aγ*3′RE genome. After 180 days in culture, 5 individual clones were either induced (+), using 40 mmol/L hemin, or not induced (−). Total RNA was isolated from each of these samples and 10 ng of the RNA was used in a semiquantitative RT-PCR assay after titration of the template amount (Fig 6). The copy number of the unrearranged vector genome, as estimated by genomic Southern analysis of BsaBI-digested DNA, is given (#) under the clone number.