Finally, to interrogate if the catalase promoter methylation plays a functional role in regulating its transcription, cells were treated in vitro with 5’-azacytidine (AZA) either alone (MEC1 and DHL6) or together with IL-2/IL-15/CpG ODN (CLL cells; n = 4)24, and catalase mRNA level was determined by qRT-PCR. Here, IL15 is linked to B-cell chronic lymphocytic leukemia.