Carboxy (C)-terminal truncations of Tpl2 (Tpl2ΔC) that occur as a result of provirus insertion in MoMuLV-induced T-cell lymphomas and Mouse mammary tumor virus (MMTV)-induced mammary adenocarcinomas in rats remove this “degron” sequence to reduce proteasomal degradation of Tpl2 [6,16,22]. The gene discussed is MAP3K8; the disease is breast adenocarcinoma.