High expression of C/EBPβ was observed in Evi1-leukemia cells. (A) Relative expression of C/EBPβ in whole BM cells derived from Evi1-leukemia mice, AML1-related leukemia mice (D171N and S291fs), a MLL/ENL-leukemia mouse, a RasGRP4-leukemia mouse, and a mock vector control mouse. Expression levels were normalized by the expression level of 18S rRNA. The expression level of the control mouse (mock ID 202) is set to 1. Plus marks indicate retroviral integration near C/EBPβ. (B) Comparison of C/EBPβ expression level between Evi1-leukemia and other leukemia. “Others” include mice transplanted with Runx1-D171N (n = 8), S291fs (n = 3), MLL-ENL (n = 1), RasGRP4 (n = 1), or mock (n = 1) transduced BM cells. (C) Schematics of 3 isoforms of C/EBPβ. AD stands for transactivating domain, and RD indicates repression domain. The horizontal arrows point to the location of the oligonucleotide primer pairs used for RT-PCR amplification. (D) Total cell lysates of the spleen cells were immunoblotted with anti-C/EBPβ Ab (Santa Cruz, C-19) and β-actin (Cell Signaling). C/EBPβ antibody (C-19) is a polyclonal antibody raised against a peptide mapping at the C-terminus of the C/EBPβ of rat origin. The spleen cells were derived from Evi1-leukemia mice, AML1-related leukemia mice (AML1-D171N and AML1-S291fs), MLL/ENL-leukemia mice, RasGRP4-leukemia mice, and a control normal mouse. Mice ID numbers are shown at the top of panels. Plus marks indicate retroviral integration near the C/EBPβ.