Serendipity & the discovery of tyrosine kinases:
"In analysing the phosphoaminoacids released by partial acid hydrolysis of polyoma virus middle T phosphorylated in vitro, Hunter used an old batch of pH 1.9 electrophoresis buffer; it so happens that phosphothreonine and phosphotyrosine do not separate on electrophoresis at pH 1.9 in acetic acid/formic acid/water buffer, but do separate at the lower pH of ‘aged’ buffer, from which the more volatile acetic acid has escaped (T Hunter, personal communication; Ushiro and Cohen, 1980)."