SEC11A encodes SPC18, the catalytic subunit of the signal peptidase complex (SPC), a membrane protein complex in the endoplasmic reticulum that catalyzes removal of N-terminal signal sequences from nascent secretory proteins 1. The active site forms a catalytic triad positioned at the ER membrane, with a transmembrane window that generates specificity for signal peptides containing hydrophobic segments shorter than 18-20 amino acids 1. Beyond its canonical role in protein processing, SEC11A expression is significantly elevated in multiple malignancies. In bladder cancer, SPC18 upregulation (54% of cases) correlates with basal-like phenotype and predicts poor survival, with knockdown inhibiting cell growth and invasiveness 2. High SEC11A expression independently associates with poor prognosis in gastric cancer (5-year survival 52.3% vs 75.9%, p<0.005) 3 and head and neck squamous cell carcinoma, where it correlates with gene amplification and altered immune infiltration patterns 4. In tongue squamous cell carcinoma, SEC11A promotes proliferation and invasion via EGFR pathway activation, and is suppressed by miR-873-5p 5. SEC11A has also emerged as a neoantigen target in colorectal cancer immunotherapy 6. Additionally, dysregulation of SEC11A appears relevant in intervertebral disc degeneration 7 and parathyroid adenoma 8, suggesting broader pathogenic roles beyond protein secretion.