Cell lines derived from T-cell ALL showed varying degrees of methylation: four (SupT1, Molt-4, PEER and TALL1) showed strong DNA methylation; three (Jurkat, CCRF-HSB2 and CCRF-CEM) showed weak-to-moderate methylation and one (Molt-3) showed no methylation. This evidence concerns the gene TNFSF13B and acute lymphoblastic leukemia.