BTK is one of the five members of the TEC family of non-receptor tyrosine kinases - along with tyrosine kinase expressed in hepatocellular carcinoma (TEC), interleukin-2-inducible T cell kinase (ITK), resting lymphocyte kinase (RLK) and bone marrow expressed kinase (BMX) - which are strongly conserved throughout evolution [28]. Here, TXK is linked to hepatocellular carcinoma.