CCND1 and mantle cell lymphoma: The pathologic hallmark of MCL is the presence of t (11;14) (q13, q32) translocation leading to an overexpression of Cyclin D1 (CCND1) which deregulates the cell cycle progression at G1‐S checkpoint by overcoming the suppressor effect of retinoblastoma 1 (RB1) and the cell cycle inhibitor p27.5