PHOX2B and cleft palate: Jackson et al. (2014) also made a Wnt1-cre;Elp1 cKO mouse, which also died postnatally, which they state was due to impaired breathing associated with cleft palate. We checked whether our Wnt1-cre;Elp1 cKO and Phox2b-cre;Elp1 cKO mice also develop cleft palate and found that although the Wnt1-cre;Elp1 cKO mice did show failure in palate fusion, the Phox2b-cre;Elp1 cKO mice did not (data not shown). This finding is perhaps not surprising because Wnt1-cre is expressed in the cranial crest whereas Phox2b-cre is not.