Potential target genes of Runx1 in B-cell development revealed by expression analysis. (A) Differentially regulated genes in pro-B/pre-B cells of Runx1-deficient mice known to encode receptor proteins or their signal effectors that are critical regulators of B-cell development. Qualitative reverse transcriptase-polymerase chain reaction (RT-PCR) analysis confirmed the levels for the Hck, Blk, and Lck genes. (B) Relative expression levels of genes encoding transcription factors from Runx1^fl/flCd79a^hCre/+ pro-B/pre-B cells were compared with that isolated from Runx1^+/+Cd79a^hCre/+ mice. Shown are genes encoding transcription factors that are critical for the development of multipotent, lymphoid-restricted, or specific B-cell developmental stages, as indicated. Qualitative RT-PCR analysis confirmed the levels of genes encoding key regulators. (C) Depicted is the relative expression ratio of 40 genes differentially regulated in Runx1-deficient pro-B/pre-B cells compared with controls and reciprocally regulated in a pro-B-cell line that expresses an inducible RUNX1 protein.