Detection of Fas transcripts in single Reed-Sternberg cells and their variants. Fas transcript was expressed by many single Reed-Sternberg cells and their variants. PCR products were run on ethidium bromide-stained 1.5% agarose gels. Positive or negative results were scored on the basis of intensity of ethidium bromide staining. Sample numbers correspond to cell numbers listed in Table 1. Molecular-weight markers (M) are labeled in base pairs.