OSR2 and cleft palate: Hence, compared to the Wnt1-cre transgene which is activated at E9.5-10.5 and throughout the neural crest-derived craniofacial mesenchyme,54 the Osr2-cre mouse line has been applied in the study of palate and tooth development more and more widely.27,55–57 Actually, several cases of cleft palate resulting from the Wnt1-cre-driving conditional allele knockouts have been identified secondary to the micrognathia by deleting the same conditional alleles via Osr2-cre.