KIRA-ELISA is used for quantitave detection of phosphorylation level of tyrosine kinase receptors. The protocol could be used for many different receptors. In our work, this protocol has been successful for TrkB and FGFR1 receptors. The underlying principle\u00a0of the assay is capturing the receptor and detecting phosphorylated tyrosine on the intracellular domain of the receptor using pan phospho-tyrosine antibody. Since tyrosine kinase receptor are phosphorylated at multiple tyrosine residues, pan phospho-tyrosine antibody detects any possible antigen on the receptor, resulting in more sensitive assay. Our assay is based on previously published bioassay by M. Sadick et. al. and M. Cazorla et. al.