Increased Tregs in preleukemic and tumor-bearing Eμ-MycT/+Parp-1−/− mice. (A) Representative flow cytometric density plots showing Tregs (CD3+CD4+CD25+FoxP3+). (B) Bar plot displaying the frequency of Tregs in preleukemic and lymphoma-infiltrated spleens and lymph nodes of mice of the indicated genotype. Values represent mean ± SEM of at least 6 mice of each genotype. (C) Immunohistochemical staining for FoxP3 of lymphoma-infiltrated lymph nodes of the indicated genotypes. (D) Quantification of FoxP3+ infiltrating cells determined by microscopic analysis. (E) Quantitative reverse transcription polymerase chain reaction analysis of Tgfb1 gene expression in BM pre-B cells. Samples were normalized according to β-actin expression levels. *P < .05, **P < .01, ***P < .001.