Hypothetical models of the mode of action of the MOZ-TIF2 fusion protein. (A) TIF2 may directly modulate the transcriptional activity of genes normally regulated by MOZ through the addition or removal of histone acetyl (Ac−) groups by its histone acetyltransferase (HAT) domain. (B) The TIF2 moiety may serve as a bridge between MOZ and CBP, and it is the HAT or other activities of CBP that leads to leukemogenic alterations in gene expression. Chromatin-associated CBP may be responsive to other cellular signals such as those mediated by jun, CREB, or STAT proteins.22-24(C) The MOZ-CBP fusion in the t(8;16),7 which is associated with a strikingly similar leukemia cell phenotype to that seen in cases with the inv(8).