+----------------SUBJ:V-N----------------+                 
      +-------COMP:N-N(of)-------+             |                 
      |           +-MOD_ATT:N-ADJ+             +COMP:V-N(in)+    
      |           |       +MOD_AT+        +-NEG+       +MOD_+    
      |           |       |      |        |    |       |    |    
 Expression of __SP__ __NODE__ mRNA does not occur in EL4 cells .
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,cell)
MOD_ATT:N-N (cell,EL4)