Introduction
The proto-oncogene Tpl-2/Cot encodes a serine/threonine kinase which is activated by provirus insertion in Moloney murine leukemia virus (MoMuLV)-induced rat T cell lymphomas and mouse mammary tumor virus (MMTV)-induced mouse mammary carcinomas. Tpl-2 kinase activates the mitogen-activated protein kinases (MAPK) and the stress-activated protein kinase (SAPK) pathways, which play an important role in the transduction of signals generated by growth factors produced in mammary epithelial neoplasms.