Use of Erbstatin as Protein-Tyrosine Kinase Inhibitor

This chapter discusses the use of erbstatin as protein-tyrosine kinase inhibitor. Streptomyces and other microorganisms produce antibiotics, anticancer agents, and enzyme inhibitors as secondary metabolites. Isolation of specific bioactive products in culture broths depends on the assay system. Erbstatin is easily inactivated in calf serum, and more stable analogs of erbstatin have been looked for. Various erbstatin analogs have been synthesized and tested for their inhibitory activity against tyrosine kinase. This analog inhibits tyrosine kinase in vitro, but are not active in vivo, because, being a polar molecule, it would penetrate the cells poorly.