+----------------COMP:V-N(in)---------------+    
      +------------SUBJ:V-N------------+         +----------MOD_ATT:N-ADJ----------+    
      +-------COMP:N-N(of)-------+     |         |      +--------MOD_ATT:N-N-------+    
      |           +-MOD_ATT:N-ADJ+     |         |      |           +--MOD_ATT:N-N-+    
      |           |       +MOD_AT+     |         |      |           |       +MOD_AT+    
      |           |       |      |     |         |      |           |       |      |    
 Expression of __SP__ __NODE__ mRNA occurs in mammary duct from pregnancy stage __SP__ .
COMP:N-N(of) (expression,mRNA)
MOD_ATT:N-ADJ (mRNA,__SP__)
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__,duct)
MOD_ATT:N-N (__SP__,pregnancy)
MOD_ATT:N-N (__SP__,stage)