Cell lines can be easily purchased from the American Type Culture Collection. Cells are cultured in RPMI media (Gibco BRL, Gaithersburg , MD ) supplemented with glutamine (200-mmol/L concentration) and fetal bovine serum (10%), in plastic flasks. Cells are then grown to 80% confluency, then harvested for genomic DNA or seeded in dishes for subsequent 5-aza-2'-deoxycytidine treatment.