Pim-1 protein kinase is nuclear in Burkitt's lymphoma: nuclear localization is necessary for its biologic effects.

Background: The Pim-1 33-kDa protein is a serine/threonine protein kinase that is capable of enhancing the rate of occurrence of c-Myc-induced lymphomas, and functions to block factor-withdrawal and genotoxic stress-induced apoptosis.

Materials And Methods: We used human lymphoma samples and tissue culture cells to examine the cellular location of this protein and its mechanism of action.

Results: We found that Pim-1 can be located in the cytoplasm, the cytoplasm and nucleus, or the nucleus of cells of normal lymph nodes, but is only located in the nucleus in Burkitt's lymphoma cells.