+----------------SUBJ:V-N---------------+                   
      +-----------COMP:N-N(of)----------+     |                   
      |           +----MOD_ATT:N-ADJ----+     |                   
      |           |      +--MOD_ATT:N-N-+     +-COMP:V-N(in)-+    
      |           |      |      +MOD_ATT+     |        +MOD_A+    
      |           |      |      |       |     |        |     |    
 Expression of __SP__ CL 6 [__NODE__] mRNA occurs in U87MG cells .
COMP:N-N(of) (expression,mRNA)
MOD_ATT:N-ADJ (mRNA,__SP__)
MOD_ATT:N-N (mRNA,6)
MOD_ATT:N-N (mRNA,[__NODE__])
SUBJ:V-N (occur,expression)
COMP:V-N(in) (occur,cell)
MOD_ATT:N-N (cell,U87MG)