STC2 (stanniocalcin 2) is a secreted glycoprotein hormone that plays crucial roles in cellular stress adaptation and calcium homeostasis. The protein functions as an anti-hypocalcemic agent involved in calcium and phosphate regulation 1. Under stress conditions including nutrient deprivation, hypoxia, and ER stress, STC2 expression is dramatically upregulated through transcriptional activation by ATF4 and p65/RelA 2. The protein operates through autocrine/paracrine mechanisms to promote cell survival by maintaining redox homeostasis, specifically by suppressing monoamine oxidase B (MAOB) expression and reducing reactive oxygen species levels 2. STC2 interacts with protein methyltransferase 5 (PRMT5), activating DNA damage repair pathways and contributing to radioresistance in cancer cells 3. In hepatocellular carcinoma, STC2 promotes cell proliferation and glycolysis while inhibiting autophagy through the PI3K/Akt/mTOR pathway 4. The protein is significantly overexpressed across multiple cancer types and correlates with poor prognosis, tumor growth, invasion, and metastasis 5. STC2 also regulates mitophagy through SQSTM1 and has been implicated in asthma exacerbation via m6A methylation-dependent mechanisms 6. These diverse functions establish STC2 as both a potential biomarker and therapeutic target in cancer treatment.