Detection of Fas antigen splice variants in MIP-101 (MIP) and CX-1 (C) cells by RT-PCR. Two transcripts of 311 and 251 bp corresponding to the membrane-bound form and soluble form of Fas antigen, respectively, are amplified after PCR of first-strand cDNA. PCR products were electrophoresed in 2% agarose and visualized under UV light after staining with ethidium bromide. Note that the intensity of both bands is lower for CX-1 relative to MIP-101 cells, suggesting decreased presence of FAS mRNA in the latter cell line. Also note that the 251-bp band is less intense then the 311-bp band, suggesting that the membrane-bound form of Fas predominates in CX-1 and MIP-101 cells.