(A) Expression of Atm, normalized to the housekeeping gene Rpl19, measured by qPCR in the indicated cell subsets isolated from Atm^+/+, Atm^+/–, and Atm^–/– mice. Each symbol represents data from an individual mouse. (B) Western blot of lysates from Lin^– bone marrow cells isolated from Atm^+/+, Atm^+/–, and Atm^–/– mice, probed with the indicated antibodies. The same membrane was simultaneously probed with all 3 antibodies using 2 LI-COR fluorescence channels (channel 1: PTEN; channel 2: ATM, TUBULIN). See complete unedited blots in the supplemental material. (C) Diagram representing the experimental setup for competitive bone marrow transplantation experiments. (D) Proportion of total blood cells, B220⁺ cells, CD3⁺ cells, and CD11b⁺ cells expressing the CD45.2 marker in the peripheral blood of lethally irradiated mice transplanted with Atm^+/+, Atm^+/–, or Atm^–/– CD45.2⁺ bone marrow cells mixed 1:1 with wild-type CD45.1⁺ competitors. Data are combined from 3 independent experiments in which transplanted cells were pooled from 2–3 donor animals per genotype; “n” indicates the number of transplanted mice. (E) Proportion of total blood cells, B220⁺ cells, CD3⁺ cells, and CD11b⁺ cells expressing the CD45.2 marker in the peripheral blood of lethally irradiated mice secondarily transplanted with bone marrow cells isolated from the primary transplanted mice describe in panel D. Data are from 2 independent experiments; “n” indicates the number of recipient mice. The gating strategy for these experiments is shown in Supplemental Figure 1, A and B. In all panels, mean and SEM are shown. *P < 0.05; **P < 0.01; ***P < 0.001; assessed by ANOVA with Tukey’s (A) or Dunnett’s (D and E; Atm^+/– and Atm^–/– compared with Atm^+/+ mice) multiple-comparison test.