ATM and mantle cell lymphoma: It has been demonstrated, however, that overexpression of cyclin D1 itself is not sufficient for development of MCL, suggesting that additional genetic events might be necessary for oncogenesis (Bodrug et al, 1994), particularly as apoptosis-related genes such as p53, INK4a/ARF, and ATM are dysregulated in MCL (Fernàndez et al, 2005; Greiner et al, 2006).