One of the requirements for an effective anti-tumour T-cell response is the generation of a large number of activated T cells, and thus understanding how T cells proliferate at the biochemical level is relevant to both basic and medical science.Due to its ability to potently expand T cells, Intedeukin-2 (IL-2) is used to treat various human cancers such as metastatic renal cell carcinoma and melanoma.More recently, attention has been focused on the related cytokine IL-15, which utilizes the same signaling pathways as IL-2.Despite the potential clinical utility of IL-2 and IL-15, the biochemical mechanism by which these cytokines promote T-cell proliferation remains incompletely defined.Recently, we identified a novel link between the She and STAT5 pathways in T-cell proliferation by demonstrating that STAT5 plays an essential role in sustaining activation of the PI3K/Akt pathway downstream of Shc.However, the mechanism by which STAT5 mediated this effect was unknown.Using the lymphocyte line Ba/F3, we have identified the kinase pim-2 as a STAT5-target gene that can enhance the Akt/p70S6K pathway.