P56lck, or LCK proto-oncogene, Src family tyrosine kinase, is a human gene encoded by LCK. It may also be known as: Tyrosine-protein kinase Lck; Leukocyte C-terminal Src kinase; LSK; Lymphocyte cell-specific protein-tyrosine kinase; Protein YT16; Proto-oncogene Lck; T cell-specific protein-tyrosine kinase; p56-LCK; Tyrosine-protein kinase Lck ; IMD22; YT16; pp58lck. The encoded protein is an enzyme with an amino acid length of 509 and a mass of 58.0 kDa. P56lck is a member of the Protein kinase superfamily, Tyr protein kinase family, SRC subfamily. Homologs of this gene exist in other organisms, including: Mouse.