EP300 and B-cell chronic lymphocytic leukemia: Because acetylation activates the transcriptional activity of STAT3 [10] and the acetyltransferase p300 acetylates STAT3 on lysine 685 residues [12], we sought to determine whether p300 acetylates STAT3 and whether acetylation contributes to the transcriptional activity of STAT3 in CLL cells.