BTK is a member of a TEC family of kinases (TFKs), a group of non-receptor kinases composed of BTK and four other kinases: tyrosine kinase expressed in hepatocellular carcinoma (TEC), IL-2 inducible T-cell kinase (ITK), resting lymphocyte kinase (RLK), and the bone-marrow tyrosine kinase gene on chromosome X (BMX) [12]. Here, TXK is linked to hepatocellular carcinoma.