DDIT3 (DNA damage inducible transcript 3) is a multifunctional transcription factor that orchestrates cellular stress responses, particularly under endoplasmic reticulum (ER) stress 1. As a member of the CCAAT/enhancer-binding protein family, DDIT3 functions as a dominant-negative regulator by dimerizing with C/EBP family members and inhibiting their transcriptional activity, while simultaneously activating pro-apoptotic and stress-response genes 1. During ER stress, DDIT3 is activated through the PERK-eIF2α-ATF4 pathway and cooperates with ATF4 to induce expression of genes involved in the unfolded protein response and apoptosis, including PUMA and death receptors like TNFRSF10B 23. DDIT3 also suppresses anti-apoptotic genes such as BCL2 and regulates inflammatory responses through caspase activation 1. Clinically, DDIT3 is most notable for its involvement in myxoid liposarcoma, where FUS/EWSR1::DDIT3 and EWSR1::DDIT3 fusions drive tumorigenesis in >95% of cases, making DDIT3 break-apart detection a valuable diagnostic marker 41. Additionally, DDIT3 activation shows therapeutic promise in pancreatic cancer and hepatocellular carcinoma by suppressing tumor stemness and enhancing sensitivity to cell death pathways 56.