Ectopically expressed Oct2 and BOB.1/OBF.1 do not bind to cognate octamer motifs in L428 cells. (A) Western immunoblot with extracts from L428 cells expressing transfected BOB.1/OBF.1 and/or Oct2. L428-Oct2 cells stably transfected with an Oct2 expression vector or control cells and transfected with the neomycin resistance gene only (L428-Neo) were supertransfected with a BOB.1/OBF.1-expression vector as indicated in “Cell lines.” One day after nucleofection, cells were harvested and used for Western blot or ChIP assays. Extracts from Namalwa cells were used as positive control. RelA-specific antibodies were used as loading control. (B) ChIP analysis of BOB.1/OBF.1, Oct1, and Oct2 binding to Ig regulatory regions in L428 cells overexpressing Oct2 and/or BOB.1/OBF.1. See Figure 1 legend.