Methylation of the tapasin and/or TAP2 promoter has been reported in melanoma and RCC cell lines and treatment with DNA demethylation agent 5-aza-2′-deoxycytidine (5-AC) results, not only in the enhancement and/or reconstitution of tapasin and TAP2, but also in TAP1 transcription and translation. The gene discussed is TAPBP; the disease is melanoma.