Rpl22 haploinsufficiency accelerates the development of cancer in a mouse model of T-cell malignancy. (A) Kaplan-Meier curves of mice of the indicated genotypes, which were killed on manifestation of outward signs of disease. Myr-Akt2;Rpl22^+/+, n = 10; Myr-Akt2;Rpl22^+/− n = 14; (B) Distribution of CD4/8 subpopulations in thymi of mice with the indicated genotypes. Single-cell suspensions of thymocytes from young adult mice (4-6 weeks) were stained with antibodies reactive CD4 and CD8. Absolute numbers of thymocytes were determined and the mean ± SD are depicted graphically to the right. Analysis was performed on a minimum of 3 mice per group and is representative of 3 experiments performed. (C) Proliferation of explanted thymocytes from MyrAkt2 Tg mice measured by BrdU incorporation. Proliferation of the indicated populations was assessed flow cytometrically by determining the extent of BrdU incorporation after a 4-hour pulse. The mean ± SD of the fraction of BrdU⁺ cells for a representative experiment is depicted graphically. Each bar represents an individual experiment involving at least 3 mice. Three experiments were performed. *P < .05. (D) Assessment of the extent of proliferation of Rpl22^+/+ and ^+/− thymic lymphoma cells by Ki-67 staining in situ. Thymic sections from the indicated mice were either stained with hematoxylin and eosin (H&E) or with anti-Ki67 antibodies to detect the number of proliferating cells. The micrograph was generated using the ×20 objective (×200 total magnification) of a Nikon Eclipse 50i microscope and a Digital Sight DS-Fi1 camera. Mean ± SEM of the thymic organ weight relative to body weight from Rpl22^+/+ (n = 6) and Rpl22^+/− (n = 9) mice at the time of sacrifice is depicted graphically below. *P < .05. Representative thymi are shown on the left. (E) Evaluation of the rate of protein synthesis in thymocytes measured by metabolic labeling. Thymocyte suspensions from mice of the indicated genotypes were metabolic labeling for 30 minutes with [³⁵S]methionine after which the counts incorporated were quantified by TCA precipitation of aliquots of the detergent lysates. Data were derived from triplicate values from 2 independent experiments. In addition, extracts were resolved directly by SDS-PAGE and visualized by fluorography (right).