Tyrosine phosphorylation plays a key role in cellular signaling. Research studies have shown that in cancer, unregulated tyrosine kinase activity can drive malignancy and tumor formation by generating inappropriate proliferation and survival signals. Antibodies specific for phospho-tyrosine have been invaluable reagents in these studies. The phospho-tyrosine monoclonal antibodies developed by Cell Signaling Technology are exceptionally sensitive tools for studying tyrosine phosphorylation and monitoring tyrosine kinase activity in high throughput drug discovery.