FIG. 1.

Targeted disruption of the mouse 53BP1 gene. (A) Map of the genomic locus surrounding the targeted exon, the targeting vector containing the PGK-neo cassette, and the targeted locus. A 5′-flanking probe used for screening ES cell clones and mice is indicated. (B) Southern blot analysis of EcoRI-digested genomic DNA. (C) Multiplex PCR genotype analysis with a primer pair for the neo gene (resulting in a 455-bp product) and a 5′ external exon (resulting in a 270-bp product). (D) Western blot of cell extracts from mouse testes with an antibody specific for the N terminus of 53BP1. (E) Immunofluorescence analysis of irradiated (1 Gy) 53BP1^+/+ and 53BP1^−/− MEFs with polyclonal antibodies raised against the N terminus of 53BP1.