CCND2 and mantle cell lymphoma: CCND1 overexpression is a hallmark of MCL development,1 while CCND2 has been shown to be upregulated in CLL cells, particularly, at the proliferation centers in lymph nodes.11,12 Concordantly, CCND2 becomes highly upregulated in CLL cells exposed to the proproliferative stimuli of our cell culture system (Figure 2A).