IER2 (immediate early response 2) is a nuclear transcription factor that functions as a key regulator of cell motility and tumor progression across multiple cancer types. Mechanistically, IER2 translocates from the cytoplasm to the nucleus upon cellular stress, where it transcriptionally activates target genes including integrin β1 (ITGB1), which subsequently activates FAK-Src-paxillin signaling to promote cell adhesion and migration 1. In colorectal cancer, IER2 expression positively correlates with metastatic potential and poor patient survival 2. Beyond its canonical roles, IER2 functions in distinct cellular contexts: in melanoma, sustained IER2 expression induces senescence via p53/MAPK/AKT pathways, causing senescent cells to secrete osteopontin that paradoxically stimulates non-senescent cell invasion 3. In chordoma, hypoxia-mediated upregulation of IER2 in cancer-associated fibroblasts promotes tumor progression through paracrine GMFG-ITGB1 signaling 4. Additionally, IER2 functions in developmental processes as an FGF signaling effector; zebrafish and Xenopus studies demonstrate IER2 requirement for ciliogenesis and left-right asymmetry establishment during embryogenesis 5 6. Clinically, elevated IER2 expression serves as a prognostic indicator of aggressive phenotype and poor survival across colorectal adenocarcinoma, hepatocellular carcinoma, melanoma, and bladder cancer.