Pim 1, Active

The proto-oncogene Pim1 belongs to a family of serine/threonine protein kinases that are highly conserved through evolution in multicellular organisms. Originally identified from Moloney murine leukemia virus induced T-cell lymphomas in mice, Pim1 is involved in the control of cytokine-mediated cell proliferation, differentiation and survival of lymphoid and myeloid cells as well as others. Expression of Pim1 can be stimulated by a variety of growth factors and is regulated at four different levels: transcriptional, post-transcriptional, translational and post-translational. Accumulating data support that the expression of Pim1 is mediated through activation of the JAK/STAT pathway. Some of the substrates of Pim1 include p21 Cip1, nuclear mitotic appartus protein, PTP-U2S and Socs-1. Recently, Pim1 has been shown to enhance the activities of p100, c-Myb and Cdc 25a and in part this might explain reported effects of Pim1 on mitogenesis. Pim1 interacts with c-Myb via the DNA binding domain and regulates its transcriptional activity.