Viral integrations decrease Sfpi1 expression and activate Mef2c expression. (A) Real-time RT-PCR analysis of total RNA isolated from spleens of leukemic animals in addition to spleen and bone marrow of normal mice using primers specific for mouse Sfpi1. Relative gene expression levels were calculated by normalizing to β-actin mRNA levels in the same sample and in normal spleen. (B) Real-time RT-PCR analysis of the same samples using primers specific for mouse Mef2c.