Global DNA methylation levels in normal and malignant B cells. Illumina 450K array data were obtained from multiple studies of normal and tumor cells.^{8-11,13,38,47,84}  Normal/tumor pairs are ordered according to degree of normal B-cell differentiation. Illumina array data were uniformly normalized; percent global methylation is represented by the average array β value × 100. Normal cells illustrated in gray. Boxes represent interquartile range, and whiskers represent minimum/maximum values. CLL chronic lymphocytic leukemia; DLBCL, diffuse large B-cell lymphoma; GCB, germinal center B cell; HSC, CD34⁺ hematopoietic stem and progenitor cell; MBC, memory B cell; MCL, mantle cell lymphoma; MM, multiple myeloma; NBC, naïve B cell; PC, bone marrow plasma cell.