A BetaGal-neo cassette was used to delete a portion of exon 9, which codes for the cytoplasmic domain essential for Fas-mediated apoptosis. Northern blot analysis revealed the expression of a truncated mRNA, representing transcripts from exons 1 though 8 in the thymus, liver, and heart. Immunoprecipitation analysis showed an absence of the wild-type protein as well as a faint presence of what the authors speculated to be a non-functional Tnfrsf6-BetaGal fusion protein.