Transient cre expression excised the floxed neo in Rps12-ps1/Xisttm1Nbd, which had a 2.5 kb sequence deletion between 5.5 and 8 kb upstream of Xist, including Rps12-ps1 and spanning a site thought to include an upstream promoter for Xist. RT-PCR showed presence of antisense transcription upstream of Xist in mutants where none is present in wild-type. (J:85305)