+MOD_ATT+SUBJ:V_PASS+COMP:V_PASS-+COMP:N-N(of)+     
     |       |           |            |            |     
 __NODE__ protein is involved in expression of __NODE__ .
MOD_ATT:N-ADJ (protein,__NODE__)
SUBJ:V_PASS-N (involve,protein)
COMP:V_PASS-N(in) (involve,expression)
COMP:N-N(of) (expression,__NODE__)