SSR2 (signal sequence receptor subunit 2) is an endoplasmic reticulum (ER) membrane protein and component of the translocon-associated protein (TRAP) complex involved in protein translocation across the ER membrane 1. As part of the TRAP complex, SSR2 functions in cotranslational protein targeting and translocation, with evidence suggesting a rate-limiting role in preproinsulin biosynthesis and glucose-dependent insulin secretion 2. SSR2 is ubiquitously expressed across organs 1. Beyond its canonical ER function, SSR2 has emerged as an oncogene in multiple cancers. In hepatocellular carcinoma (HCC), SSR2 is significantly upregulated and promotes cell proliferation, migration, and invasion while inhibiting apoptosis; higher SSR2 expression correlates with poor prognosis 3. SSR2 downregulation sensitizes HCC cells to cisplatin by suppressing Yes-associated protein phosphorylation and activating Hippo pathway signaling 4. In gastric cancer, SSR2 upregulation via the lncRNA RP11-874J12.4/miR-3972 axis confers chemoresistance to docetaxel and cisplatin 5. SSR2 also plays unexpected roles in innate immunity, as it interacts with STING to facilitate interferon-beta induction following viral infection and intracellular DNA sensing 6, suggesting involvement in both cancer progression and host defense mechanisms.