Figure 1.

Overexpression of Gfi1B causes down-regulation of RAG1-GFP transcript levels. (A) Flow cytometric analysis of RAG1-GFP expression in RAG1-GFP^high cells isolated from a reporter mouse where GFP replaces exon1 of Rag1 and infected with a retroviral construct overexpressing the Gfi1B ORF or empty vector control. Data are representative of five independent experiments. (B) Flow cytometric analysis of RAG1-GFP expression in RAG1-GFP^high cells overexpressing Gfi1. RAG1-GFP levels were measured 3 d after infection. Data are representative of three independent experiments. (C) Quantitative RT-PCR of Rag1 and Rag2 mRNA transcripts in RAG1-GFP^high cells infected with a Gfi1B-ER construct and treated (+) or not (−) with tamoxifen (4-OHT) for 12 h. Numbers 1–3 indicate biological replicates. Levels are expressed relative to HPRT transcripts. Error bar represents standard deviation of triplicate PCR assays. (D) Flow cytometric analysis of RAG1-GFP^high cells overexpressing Gfi1b cultured in the presence or absence of 2.5 µM of the Abl kinase inhibitor STI-571 (Gleevec) for 12 h. Data are representative of two independent experiments. (E) Flow cytometric analysis of RAG1-GFP^high cells infected with a retroviral Gfi1b-ER construct. Cells were treated or not with tamoxifen (4-OHT) for 5 d and, where indicated, were washed and cultured for 9 d thereafter. Data are representative of two independent experiments.