MAPK (mitogen-activated protein kinase) pathways are among the most frequently deregulated signalling events in cancer. Among the critical targets of MAPK activities are members of the AP-1 (activator protein 1) transcription factor, a dimeric complex consisting of Jun, Fos, Maf and ATF (activating transcription factor) family DNA-binding proteins. Depending on the cellular context, the composition of the dimeric complexes determines the regulation of growth, survival or apoptosis. JNK (c-Jun N-terminal kinase), p38 and a number of Jun and Fos family proteins have been analysed for their involvement in oncogenic transformation and tumour formation. These data are also emerging for the ATF components of the AP-1 factor. The aim of the present review is to provide an overview of the functions of two ATF family proteins, ATF2 and ATF7, in mammalian development and their potential functions in tumour formation.