+---------SUBJ:V-N--------+-----COMP:V-N(in)-----+    
      +----COMP:N-N(of)---+     |         +MOD_ATT:N-AD+    
      |            +MOD_AT+     |         |     +MOD_AT+    
      |            |      |     |         |     |      |    
 Expression of __NODE__ mRNA occurs in __SP__ heart tissue .
COMP:N-N(of) (expression,mRNA)
MOD_ATT:N-ADJ (mRNA,__NODE__)
SUBJ:V-N (occur,expression)
COMP:V-N(in) (occur,toilet)
MOD_ATT:N-ADJ (toilet,__SP__)
MOD_ATT:N-N (toilet,heart)