Abstract: This invention relates to growth regulatory proteins expressed in various disease states, especially receptor tyrosine kinases and similar growth factor receptors. Prior to the Applicants invention, it was not clear that specific antibodies could be generated that recognized peptide epitopes comprising phosphotyrosine in the context of its surrounding amino acid sequence. Applicants generated antibodies to such phosphotyrosine specific peptides, distinct from antibodies that recognize only phosphotyrosine itself. The invention includes methods for producing phosphopeptide specific antibodies by removing contaminating antibody specificities by negative and/or positive selections. Phosphospecific antibodies and their uses in immunodetection, diagnostic or therapeutic applications are also disclosed.