These observations might explain why while IL-21 has been found to promote apoptosis of DLBCL cell lines via STAT3 activation and c-Myc expression resulting in tumour regression and prolonged survival of mice16,17, IL-21 treatment of EBV-positive DLBCL cell lines results in increased cell proliferation18. The gene discussed is MYC; the disease is diffuse large B-cell lymphoma.