DDIT3 and neoplasm: The results revealed significantly elevated expression levels of ER stress marker C/EBP homologous protein (CHOP) (Fig. 6d), glucose-regulated protein 78 (GRP78), and PKR-like endoplasmic reticulum kinase (PERK) (Additional file 1: Fig. S23) in tumor tissues from the HAQ/223Ra@HNPs group, suggesting that alpha radiation effectively induces ER stress and activates the downstream unfolded protein response (UPR) pathway.