Activating transcription factor 2, also known as ATF2, is a member of the leucine zipper family of DNA-binding proteins that binds to the cAMP response element. Its activity is enhanced after phosphorylation by stress-activated protein kinases such as c-Jun N-terminal kinase and p38. ATF2 has been found to be a target of the JNK signal transduction pathway and mediate adenovirus E1A-inducible transcriptional activation. ATF2 is also been reported playing roles in TGF-β signaling pathway. It has been shown that the transcription factor ATF2 is bound by a hetero-oligomer of Smad3 and Smad4 upon TGF-β stimulation. Studies indicate that ATF-2 plays a central role in TGF-β signaling by acting as a common nuclear target of both Smad and TAK1 pathways.