Hint1, or histidine triad nucleotide-binding protein 1, belongs to the first branch of the HIT superfamily. It hydrolyzes adenosine 5'-monophosphoramidate substrates such as AMP-morpholidate, AMP-N-alanine methyl ester, AMP-alpha-acetyl lysine methyl ester and AMP-NH2. Hint1 also inhibits the activity of the transcription factors AP1, MITF and USF2, as well as influences the transcription process of the Wnt/beta-catenin pathway. In addition, mammalian Hint1 has been suggested to have some tumor suppressor activity.