SCGB2A1 (secretoglobin family 2A member 1), also known as mammaglobin B, is a secreted protein with emerging roles in cancer biology and immune regulation. The protein may bind androgens and other steroids, and can be transcriptionally regulated by steroid hormones [UniProt]. At the molecular level, SCGB2A1 interacts with PI3K pathway components; specifically, it was identified as a PIK3CA-interacting protein that represses PI3K-AKT signaling in breast cancer 1. In cancer pathology, SCGB2A1 expression correlates with poor prognosis across multiple malignancies. In colorectal cancer, SCGB2A1 is an independent prognostic factor associated with chemoresistance, radioresistance, and cancer cell stemness 2. In ovarian cancer, SCGB2A1 is highly differentially expressed across all major histological types and serves as a novel tumor-associated antigen capable of eliciting CD8+ cytotoxic T-lymphocyte responses 3. In endometrial cancer, lower SCGB2A1 expression predicts worse overall survival and correlates with reduced immune checkpoint blockade response 4. Clinically, SCGB2A1 represents a dual-faced biomarker: high expression indicates poor outcomes in colorectal cancer but favorable prognosis in endometrial cancer. SCGB2A1 is downregulated in mild Alzheimer's disease tear fluid, suggesting potential as a neuroinflammation biomarker 5. Emerging therapeutic strategies propose modulating SCGB2A1 expression to enhance anti-tumor immunity in breast cancer 6.