+----------------SUBJ:V-N----------------+                                       
      +-------COMP:N-N(of)-------+             +-----------COMP:V-N(in)-----------+    
      |           +-MOD_ATT:N-ADJ+             |         +-------MOD_ATT:N-N------+    
      |           |       +MOD_AT+        +-NEG+         |                +MOD_ATT+    
      |           |       |      |        |    |         |                |       |    
 Expression of __SP__ __NODE__ mRNA does not occur in uterus from non pregnant __SP__ .
COMP:N-N(of) (expression,mRNA)
MOD_ATT:N-ADJ (mRNA,__SP__)
MOD_ATT:N-ADJ (mRNA,__NODE__)
SUBJ:V-N (occur,expression)
NEG (occur,not)
COMP:V-N(in) (occur,__SP__)
MOD_ATT:N-N (__SP__,uterus)
MOD_ATT:N-ADJ (__SP__,pregnant)