~Src is a member of a very large group of protein kinases.  There are hundreds of different types of protein kinases found in eukaryotic cells!  Shown below is the "family tree" of protein kinases. 
 
    ~In general, protein kinases are involved in networks of signals that conduct several different cellular functions. 

    ~The Src protein was the very first tyrosine kinase to be discovered and identified. (The Src protein is only found in multicellular organisms.)

    ~ Src tyrosine kinase passes important signals from protein receptors to the respective proteins.  In particular, src works with proteins that control cell growth.