CDKN1A and lymphoma: We showed a greater speed of growth of lymphoma cells compared to that of the lymphocytes, accompanied by a down-expression of genes for inhibitory proteins of cyclin-dependent kinase (CDK) complexes, such as CDKN1A (p21), which acted at the G1/S and G2/M cell cycle checkpoints [19], and CDKN1B (p27), which played a critical role in regulating the G1/S transition [20].