Among the ∼8000 genomic DNA-binding sites that are occupied by OBF1 in conjunction with OCT1 or OCT2, there are key factors for the GC B-cell gene expression program. Several of these are indicated here. These factors are induced by binding of OBF1 and OCT (+). Furthermore, OBF1/OCT1/OCT2 negatively regulate expression of IRF4 (−), thereby further suppressing an exit from the GC B-cell program both in normal B cells and in some types of B-cell lymphomas.