ITK and hepatocellular carcinoma: BTK belongs to a five-member family of Tec non-receptor tyrosine kinases composed of tyrosine kinase expressed in hepatocellular carcinoma (TeC), BTK, interleukin-2-inducible T-cell kinase (ITK), bone marrow-expressed kinase (BMX), and tyrosine protein kinase/redundant-resting lymphocyte kinase (TXK/RLK); these kinases are mainly expressed on hematopoietic cells [19].