DDI1 (DNA-Damage Inducible 1 Homolog 1) is a protein involved in essential cellular functions such as DNA repair, cell cycle control, and the ubiquitin-proteasome pathway. It plays a vital role in the response to DNA damage by functioning as a ubiquitin-dependent protease, aiding in the degradation of specific proteins to preserve cellular health. Because of its diverse functions, DDI1 is crucial for protecting cells from stress and may be associated with cancer and other diseases linked to DNA damage and repair.