+---------SUBJ:V-N--------+                                   
      +----COMP:N-N(of)---+     +--COMP:V-N(in)--+                  
      |            +MOD_AT+     |         +MOD_AT+COMP:N-N(of+      
      |            |      |     |         |      |           |      
 Expression of __NODE__ mRNA occurs in __SP__ islets of Langerhans .
COMP:N-N(of) (expression,mRNA)
MOD_ATT:N-ADJ (mRNA,__NODE__)
SUBJ:V-N (occur,expression)
COMP:V-N(in) (occur,islet)
MOD_ATT:N-ADJ (islet,__SP__)
COMP:N-N(of) (islet,Langerhans)