Changes in transcription factor assembly at the Cd19 enhancer during B-cell differentiation. In vivo DMS footprinting assays were performed on purified primary cells at various stages of B-cell differentiation (A) and pro-B cell lines (B). DMS-modified and piperidine-cleaved DNA was amplified using LM-PCR with primers specific for the enhancer region. Symbols are as in Figure 2. (C) E2A and EBF bind to the enhancer in pro-B cells in the presence or absence of PAX5. ChIP assays were performed using Pax5-ER cells induced with OHT and antibodies specific for E2A, EBF, and PAX5. The enrichment was measured at the enhancer and a downstream region at +10 kb. The value for relative enrichment was normalized against the enrichment at 45 s rRna promoter. Data are representative of 2 independent experiments performed in triplicate.