LCK(Lymphocyte cell-specific protein-tyrosine kinase) is also named as LSK,p56-LCK and a nonreceptor protein-tyrosine kinase of the SRConcogene family that is involved in transduction of T-cell receptor-mediated activation.It is implicated in the control of lymphocyte growth by virtue of its overexpression in some lymphoid malignancies and its transforming activity in heterologous systems.It has 3 isoforms produced by alternative splicing.