The viral and cellular forms of the Src protein tyrosine kinases take
a prototypic role in oncology and signal transduction research, by vir
tue of being holders of an impressive number of 'firsts'. Our understa
nding of the biochemistry and physiology of Src has therefore always b
een used as a reference for our general advancement in the field of pr
otein phosphorylation and growth control. The recent solution of the c
rystal structure of two members of the Src family((1,2)) represents a
milestone in these disciplines and, as usual, provides a general looko
ut post for developments to come.