This allele lacks exons 2 and 3, which encode a portion of the DNA-binding high mobility group domain and the entire transactivation domain. It can be derived from Sox9tm1Gsr by cre recombinase excision of the loxP-flanked region containing exons 2 and 3 or from Sox9tm2Gsr by simultaneous excision of exons 2 and 3 and of a loxP-flanked neo cassette (which has been deleted in Sox9tm1Gsr). (J:75124)