Il6st^tm1Ard

The 4 signal transducer and activator of transcription (STAT) sites in exon 18 were deleted by homologous recombination of a construct containing two missense mutations (disrupting the first site) and an IRES-neo cassette (replacing the other 3 sites). The missense mutations were at codons 765 (tyrosine to phenylalaine) and 768 (glutamine to alanine). A nonsense mutation was engineered at codon 769, immediately preceding the IRES-neo cassette. Transcription of the targeted allele was verified by Northern blot analysis. (J:79555)