Cyclin D1 is a chief regulator of the cell cycle and transcriptional processes [1]. Among other human cancers, it is expressed in mantle cell lymphoma (MCL), where its encoding gene CCND1 is activated by the t(11;14)(q13;q32) in almost 100% of cases. Through an alternative splicing, CCND1 generates two mRNAs, cyclin D1a and D1b, which differ in their C-terminus. It is currently thought that cyclin D1b could represent a nuclear oncogene. In clinical practice, identification of cyclin D1 over-expression...