The cell death response of the melanoma lines was dependent on the MGMT level, which was shown by (1) the existence of an inverse correlation between the MGMT activity and TMZ-induced apoptosis, (2) inhibition of MGMT by O6-benzylguanine that sensitised all MGMT-expressing melanoma lines, and (3) transfection with MGMT which caused TMZ apoptotic resistance. The gene discussed is MGMT; the disease is melanoma.