Induction of Gfi1b by E47 in E2A^−/− T-cell lymphomas. (A) Fold induction of the indicated genes 24 hours after infection of E2A^−/− lymphomas 0531 (▪) and 1.F9 (⊡) with GFP-producing (S003) or E47 plus GFP-producing (S003-E47) retrovirus. Expression levels were determined using Affymetrix 430 2.0 gene arrays and the fold increase in gene expression in E47 plus GFP-expressing cells as compared to GFP-expressing cells is presented (log₂ scale) for genes that showed a greater than 3-fold induction in both cell lines. (B) Northern blot analysis of RNA isolated from sorted GFP⁺ lymphomas 24 hours after infection with MigR1 (−) or MigR1-E47 (E47) retrovirus. MEL cells were included as a positive control. Total RNA is shown on the bottom and the blot was probed sequentially with Gfi1b and Gfi1 cDNA. (C) Quantification of Gfi1b mRNA by QPCR in 0531 or 1.F9 cells infected with MigR1 (▪) or MigR1-E47 (□). The level of Gfi1b mRNA was determined relative to HPRT mRNA by the ΔC_T method and relative expression was determined using the formula 2^−ΔΔCT. The standard error of triplicate measurements is shown. (D) QPCR analysis of Gfi1b mRNA in DN2 (Lin⁻CD117⁺CD25⁺) and DN3 (Lin⁻CD117⁻CD25⁺) cells isolated from E2A^+/+ (⊡) or E2A^−/− (▪) thymocytes.