Src kinase-mediated signaling in leukocytes.

A concert of antigens, antibodies, cytokines, adhesion molecules, lipid factors, and their different receptors mediate leukocyte development and inflammatory responses. Regardless of the stimulus and receptor type, members of the Src family of protein tyrosine kinases (PTKs) play a critical role in initiating the numerous intracellular signaling pathways. Recruited and activated by the receptor, these Src PTKs amplify and diversify the signal. Multiple pathways arise, which affect cell migration, adhesion, phagocytosis, cell cycle, and cell survival. Essential nonredundant properties of Src PTKs have been identified through the use of gene targeting in mice or in the somatic cell line DT40. Because of their role in mediating leukocyte proliferation and activation, Src PTKs serve as excellent drug targets. Inhibitors of Src family members and dependent pathways may be useful in the treatment of human diseases similar to drugs known to inhibit other signal transduction pathways.