ERRFI1 (ERBB receptor feedback inhibitor 1) is a multifunctional adapter protein that serves as a negative regulator of EGFR family signaling pathways 1. The protein functions by inhibiting EGFR catalytic activity through interference with receptor dimerization and blocking autophosphorylation of EGFR, ERBB2, and ERBB4 2. ERRFI1 expression is regulated by glucocorticoids, being identified as one of the most frequently upregulated genes in brain tissue following glucocorticoid treatment 3. In cancer contexts, ERRFI1 acts as a tumor suppressor through its inhibition of EGFR signaling, with its downregulation leading to EGFR pathway activation 24. The protein's mRNA stability is enhanced by NAT10-mediated N4-acetylcytidine modifications, and its expression affects cancer cell proliferation, migration, and therapeutic responses 5. ERRFI1 shows context-dependent effects in different cancer types, functioning as a tumor suppressor in some breast cancer models while conferring pro-tumorigenic effects in highly metastatic triple-negative breast cancer 4. The protein also plays roles in immune regulation and has been identified as a potential biomarker for obstructive sleep apnea and atherosclerosis 6.