DDI1 (DNA-Damage Inducible 1 Homolog 1) is a protein involved in essential cellular processes such as DNA repair, regulation of the cell cycle, and the ubiquitin-proteasome system. It plays a crucial role in responding to DNA damage by functioning as a ubiquitin-dependent protease, aiding in the degradation of specific proteins to sustain cellular health. Due to its multifunctional roles, DDI1 is vital for protecting cells from stress and may be associated with cancer and other diseases related to DNA damage and repair.