CCND1 and mantle cell lymphoma: A retrospective immunohistochemistry (IHC) analysis on a cohort of 42 MCL patients followed at a single institution confirmed that staining for cyclin D1 defined two groups of patients: those with mostly nuclear staining (e.g. patient #1) and those with both nuclear and cytoplasmic staining (e.g. patient #2, Fig. 1C).