MATK belongs to tyrosine protein kinase family, CSK subfamily. It inactivates Src family kinase activity by specifically phosphorylating their C-terminal regulatory tyrosine residue and may plays a significant role in the signal transduction of hematopoietic cells. MATK binds to the phosphorylated Tyr568/570 sites on c-KIT to which FYN binds and leads to the down-regulation of FYN. MATK has been shown to be involved in signaling in some cases of breast cancer.