MAGEA4 and melanoma: In addition, the treatment with the DNA hypomethylating agent 5-aza- 2’-deoxycytidine was able to induce a de novo expression of MAGE-A3, MAGE-A4, GAGE 1-2, GAGE 1-6 and SSX 1-5 in both ABCG2+ and ABCG2- melanoma cells derived from the same parental cell culture.