It primarily inhibits cysteine proteases such as tissue proteases K, L, S, and V. SERPINB3 has been found to have antiapoptotic, proproliferative, and promigratory effects and is frequently overexpressed in squamous cell carcinomas such as cervical cancer, lung cancer, esophageal cancer, and head and neck tumors [79]. This evidence concerns the gene CTSB and squamous cell carcinoma.