AP-1 in mouse development and tumorigenesis

Genetically modified mice have provided important insights into the biologi cal functions of the dimeric transcription factor complex AP-1, Extensive a nalyses of mice and cells with genetically modified Fos or Jun proteins pro vide novel insights into the physiological functions of AP-1 proteins. Usin g knock-out strategies it was found that some components, such as c-Fos, Fo sB and JunD are dispensable, whereas others, like c-Jun, JunB and Fra-1 are essential in embryonic development and/or in the adult organism. Besides t he specific roles olf AP-1 proteins in developmental processes, we are begi nning to obtain a better molecular understanding of the cell-context depend ent function of AP-1 in cell proliferation and apoptosis, in bone biology a s well as in multistep tumorigenesis.