[5] This enzyme phosphorylates tyrosine residues located in the C-terminal end of Src-family kinases (SFKs) including SRC, HCK, FYN, LCK, LYN and YES1.

[6][7] This Non-receptor tyrosine-protein kinase plays an important role in the regulation of cell growth, differentiation, migration and immune response.

[8][9][10][11] Upon phosphorylation by other kinases, Src-family members engage in intramolecular interactions between the phosphotyrosine tail and the SH2 domain that result in an inactive conformation.

[13] Tyrosine-Kinase CSK is mainly present in the cytoplasm, but also found in lipid rafts making cell-cell junction.

[12] Csk's interaction with a phosphatase ("Lyp", gene product of PTPN22) is possibly associated with the increased autoimmune diseases associated with PTPN22 mutations.