Fig. 4.

Enhanced genomic instability in Atm^−/−Casp2^−/− lymphomas and premalignant lymphocytes. (A) Representative fluorescent images (magnification of 100×) of DAPI-stained metaphase spreads (with chromosome counts indicated) from Atm^−/− and Atm^−/−Casp2^−/− thymic lymphomas. Quantification of metaphases showing frequencies of diploid, low-grade aneuploid, and high-grade aneuploid karyotypes in (B) thymic lymphomas derived from Atm^−/− (n = 3) and Atm^−/−Casp2^−/− (n = 8) mice and (C) splenocytes and (D) thymocytes derived from WT (n = 4), Casp2^−/− (n = 4), Atm^−/− (n = 3), and Atm^−/−Casp2^−/− (n = 5) premalignant mice. A total of 80 (thymic lymphomas) and 50 (splenocytes and thymocytes) metaphases were counted per mouse (***P < 0.001, χ² test).