On the cover: Hematopoietic cancers, such as the follicular lymphoma pictured on the cover, frequently contain chromosomal translocations. However, the molecular mechanisms behind these DNA breakage and reshuffling events are largely unidentified. In this issue of Cell, Tsai et al. (pp. 1130–1142) show that CpG dinucleotides, like that colored in the molecular structure on the cover, are hotspots for pro-B/pre-B stage translocations—the most common translocations in human cancer. On the basis of the molecular activities occurring in pro-B/pre-B cells, they propose a theory to explain the apparent lineage specificity, stage specificity, and breakage at CpGs. The structure was adapted from PDB 3C2I and generated in UCSF Chimera. The histologic photo of the follicular lymphoma was a generous gift of Dr. Bharat Nathwani, USC.