Figure 1. Construction and characterization of the CKO1, CKO2 and CKO3 mice.

(A) The exon structure of the p53flox and deleted p53^ΔE5-6 (Del) alleles and RT-PCR strategy. Positions for the primers, P1-8, are illustrated. (B) Schematic drawing of the genetic configurations of CKO1-3 mice. All the mutant mice analyzed developed brain tumors including those in early stages. The number in parenthesis shows the number of mutant mice that developed high-grade brain tumors. (C) Survival curves of control and CKO1-3 mutant mice. “p” value was obtained from Kaplan/Meier Survival Test. (D) The percentage of malignant astrocytic gliomas and medulloblastomas observed in the mutant mice with high-grade brain tumors. Of note, one of 23 CKO1 mice developed both malignant glioma and medulloblastoma. (E, F) Genomic DNAs isolated from the tails (T) and brain tumors (BT, arrows) of CKO1-3 mice were subjected to PCR analysis for the p53 (E) and Nf1 alleles (F). WT, wild-type allele; flox, p53flox allele; “*”, p53 pseudogene; “Δ”, deleted p53 allele; KO, Nf1 knockout allele. (G) RT-PCR analysis showing an aberrant transcript, lacking exons 5 and 6, produced from the mutant alleles in brain tumors including malignant glioma and medulloblastoma (Mb). The p53 full-length cDNAs were amplified from colon cancers of the Smad3^−/− mice, serving as a positive control; the p53-null cDNAs from malignant gliomas (MG) of the hGFAP-cre+;p53^KO/KO;Nf1^flox/flox; mice were used as a negative control. Of note, the p53-null allele produces a truncated transcript lacking exons1 to 6.