In this study, we investigated the effect of 5-azacytidine on the transcription of the POU2F1 gene and showed that it selectively suppresses the transcription from the tissue-specific L promoter of the POU2F1 gene and reduces the concentration of the Oct-L isoform in tumor cells of Namalwa Burkitt’s lymphoma. The gene discussed is POU2F1; the disease is neoplasm.