Deregulated Mef2c expression accelerates the development of Sox4-induced leukemia. (A) Survival curve of lethally irradiated mice receiving MSCV-Mef2c-infected, MSCV-Sox4-infected, or double-infected bone marrow cells. (B) MPO staining of a representative leukemic spleen from an animal receiving double-transduced cells (top) or normal spleen (bottom). Original magnification, 100 ×. (C) Northern blot analysis of total RNA prepared from the spleens of 2 leukemic mice receiving double-infected bone marrow and normal mice using probes specific for Sox4 and Mef2c. β-Actin was used as a control for RNA loading.