+------------COMP:V-N(in)-----------+    
      +---------SUBJ:V-N--------+         +------MOD_ATT:N-ADJ------+    
      +----COMP:N-N(of)---+     |         |      +----MOD_ATT:N-N---+    
      |            +MOD_AT+     |         |      |           +MOD_AT+    
      |            |      |     |         |      |           |      |    
 Expression of __NODE__ mRNA occurs in mammary gland from virgin __SP__ .
COMP:N-N(of) (expression,mRNA)
MOD_ATT:N-ADJ (mRNA,__NODE__)
SUBJ:V-N (occur,expression)
COMP:V-N(in) (occur,__SP__)
MOD_ATT:N-ADJ (__SP__,mammary)
MOD_ATT:N-N (__SP__,gland)
MOD_ATT:N-N (__SP__,virgin)