ALL cell lines as models for (de)methylation. (A) Heatmap showing methylation levels in the t(4;11)-positive B-ALL cell lines SEMK2 (light green dot) and RS4;11 (dark green dot) of genes most significantly methylated in t(4;11)-positive infant ALL patients (red dots) compared with normal bone marrow (blue dots). (B) Heatmaps showing methylation levels of these genes after exposure to zebularine. These methylation levels were compared with the average methylation levels as determined from normal bone marrow samples (n = 7). (Bi) SEMK2 cell line and (Bii) RS4;11 cell line. (Ci-vi) Graphs displaying the mean and the standard error of the mean of changes in methylation levels after zebularine exposure. Genes were divided into 3 groups for each cell line according to the degree of responsiveness to zebularine. (Ci-iii) SEMK2 cell line; (Civ-vi) RS4;11 cell line.