Src (pronounced "sarc" as it is short for sarcoma) is a proto-oncogene encoding a tyrosine kinase. It belongs to a family of non-receptor tyrosine kinases called Src family kinases. c-Src is made up of 6 functional regions: Src homology (SH) 4 domain (SH4 domain), unique region, SH3 domain, SH2 domain, catalytic domain and short regulatory tail. When Src is inactive, the phosphorylated tyrosine group at the 527 position interacts with the SH2 domain which helps the SH3 domain interact with the linker domain and consequently keeps the inactive unit tightly bound. The activation of c-Src causes the dephosphorylation of the tyrosine 527 which causes the structure to be destabilized and then result in the opening up of the SH3, SH2 and the kinase domains and autophosphorylation of tyrosine 416. The activation of the c-Src pathway has been observed in about 50% of tumors from colon, liver, lung, breast and the pancreas.