ABSTRACT
Bioassays had to be established to determine the activity and selectivity of kinase inhibitors. Various in vitro and in vivo tests were established to demonstrate whether that inhibition resulted in the prevention of signal transduction, cell growth and tumor growth. A lead compound was required which had some kinase inhibitory effect, and which could be modified to improve its activity and selectivity. Kinase inhibitors for the epidermal growth factor (EGF)-receptor must be highly selective, because there are many other kinds of kinase enzymes present in the cell. These include other tyrosine kinases, as well as kinases that phosphorylate the serine and threonine residues of proteins. Since the kinase activity of the EGF-receptor leads to the phosphorylation of tyrosine residues within the cell, a high throughput ELISA assay was developed which measured the total tyrosine phosphorylation resulting from exposure to EGF and how these levels were affected when an inhibitor was present.
