Fig. 1.

Mouse lines were generated for a conditional medulloblastoma model. (A) For the Ptc1 conditional mouse line, a targeting vector was designed for which exons 1B, 1, 1A and 2 were flanked by Lox511 sites at the locations of KpnI and SacI restriction endonuclease sites. This F1–2p allele (not shown) contains the neomycin resistance gene (Neo positive), whereas the F1–2m allele has had the FRT-flanked neomycin resistance gene removed by Flpe (Neo minus). In the presence of Cre, the inactivated DEL1–2 allele is generated. The positions of PCR genotyping primers ck192, ck295, ck296 and ba97 are shown. (B) Southern hybridization of ES cell clones using an external probe demonstrates an 8.2 kB downshift for multiple samples that harbor the Ptc1 targeted conditional modification. (C and D) We have previously described generation of the Pax7^ICNm mouse and its myogenic expression. Shown here is the central nervous system lineage of Pax7 in neonates. For mice doubly heterozygous for the Pax7^ICNm allele and an eYFP reporter allele, the Pax7 lineage includes both the midbrain (mb) and the cerebellum (cbl).