Figure 1.

A conditional allele expressing TLS-CHOP. (A) Targeting vector and targeted allele of Tls (“m2”) before and after Cre-mediated site-specific recombination. The loxP-flanked Neo cassette and juxtaposed human CHOP coding region represent an in-frame interruption of the Tls gene. Before Cre-mediated recombination, the allele encodes a TLS-Neo fusion protein, whereas after recombination it encodes TLS-CHOP. (B) Genomic PCR analysis of the targeted allele. The 3S and 4AS primers lie outside the targeting vector (horizontal arrows). (C) Site-specific recombination-dependent expression of TLS-CHOP. Shown is a Western blot of whole-cell extracts from embryonic fibroblasts with (m2/+) or without (+/+) the mutant Tls allele that had been transduced with a Cre-expressing retrovirus. Position of the TLS-CHOP protein is indicated by the arrow. TLS serves as a loading marker.