It has been shown that the expression of p16Ink4a and Arf, which are products of the Cdkn2a tumor suppressor locus that are involved in cell cycle regulation and used as molecular signatures of aging in rodent and human tissues [36], is significantly increased in all stages of B lymphopoiesis in old mice, particularly in pro-B and pre-B cells. Here, CDKN2A is linked to neoplasm.