BSAP binds to the exon 1 of PRDM1 in vivo. Chromatin was prepared from Daudi cells as a B-cell line expressing BSAP factor (lanes 1-2,5), and from NCI-H929 cells as a PC cell line not expressing BSAP (lanes 3-4). ChIP analysis was performed using a specific anti-BSAP antibody (lanes 1,3) or an unspecific antibody isotype as negative control (lanes 2,4). Products from final PCR analysis using primers specific to the PRDM1 promoter, CD19 promoter (as BSAP binding positive control), and exon 4 from GADPH (as BSAP binding negative control) were resolved by agarose gel. The input DNA for Daudi was amplified in lane 5. A representative experiment from 3 ChIP experiments is shown. mw indicates molecular weight marker.