PIM-2 belongs to a family of cytoplasmic serine/threonine protein kinases that consists of two other members, PIM-1 and PIM-3. Expression of this protein is regulated by hematopoietic cytokines. PIM-2 is most abundantly expressed in hematopoietic tissues, spleen, thymus, and peripheral blood leukocytes, as well as in testis, small intestine, and colon. It is also highly expressed in human leukemic and lymphoma cell lines. The gene is also expressed in primary spermatocytes. The results suggest a role for PIM-2 in proliferating cells as well as during meiosis. PIM-2 is thought to be a mediator of p53 mediated apoptosis inhibition by interleukin 3, which supports its role in the formation of various tumors including lymphomas.