PTK2 and neoplasm: For example, in bladder cancer, ST8SIA1 suppresses cell proliferative, invasive, and migratory capabilities by inhibiting the JAK/STAT3 pathway.21ST8SIA1 knockout dramatically blocks tumor metastasis and growth of triple-negative breast carcinoma via the FAK-AKT-mTOR signaling pathway.22 These indicate that ST8SIA1 may work as a tumor activator or suppressor depending on cancer types.