Profile: Selleck Chemicals is specialized in providing novel kinase inhibitors for cell signaling & oncology research. Receptor tyrosine kinases (RTKs) are the high-affinity cell surface receptors that transmit extracellular signals into the cell. Many RTK classes have been identified, such as EGFR family, FGFR family, VEGFR family, RET receptor family, and Eph receptor family. Over-expression or functional mutations of receptor tyrosine kinases lead to uncontrolled cell growth and cancer. Ispinesib mesilate(SB-715992) is an agent which inhibits the mitotic kinesin KSP (Eg5) with a Ki of 0.6 nM, and has cytotoxic activity at less than 10 nM in a spectrum of tumor cell lines. Ispinesib mesilate is a potent inhibitor of kinesin spindle protein, a kinesin motor protein essential for the formation of a bipolar mitotic spindle, and cell cycle progression through mitosis. Atazanavir is an anti-retroviral drug of the protease inhibitor (PI) class. Like other anti-retrovirals, it is used to treat infection with human immunodeficiency virus (HIV). Staurosporine is a natural product originally isolated from the bacterium, Streptomyces staurosporeus. The main biological activity of staurosporine is the inhibition of protein kinase by the prevention of ATP binding to the kinase. This is achieved through the stronger affinity of staurosporine to the ATP-binding site on the kinase. Staurosporine is a prototypical ATP-competitive kinase inhibitor, in that it binds to many kinases with high affinity, though with little selectivity.