Squamous cell carcinoma antigen (SCC-Ag, also called SCCA, with isoforms SCCA1/SERPINB3 and SCCA2/SERPINB4) is a glycoprotein first isolated from squamous carcinomas and is widely studied as a serum tumor marker in cervical squamous cell carcinoma [116]. Here, SERPINB4 is linked to cervical squamous cell carcinoma.