The Smek (Suppressor of mek null) gene is described and characterized. Smek acts in the stress response pathway of animals by binding to and enhancing the transcription of FOXO, thereby providing the link between the stress response pathway and the insulin/IGF-1 pathway. Given the link between both the stress response pathway and the insulin/IGF-1 pathway and longevity, Smek1 represents an essential target for modulation of life span and the stress response. Methods of increasing life span and stress tolerance by modulation of Smek activity are disclosed, as are screening methods for identifying compounds that modulate Smek activity. In addition, recombinant animals expressing the Smek gene that have a longer life span and enhanced stress tolerance, and methods of using the Smek genet to modulate both longevity and stress tolerance, are described.