NOTCH1 and lymphoma: However, similar to lymphomas from Atm KO or Trp53 KO mice, in which deletions of tumor suppressor gene Pten and mutations/amplifications of Notch1 oncogene are often identified, the majority (80%) of the sequenced lymphomas from Brca1−/−;Trp53bp1−/− mice contained SVs at Pten and/or Notch1 locus (Fig. 5d).