+------------SUBJ:V-N------------+                     
      +-------COMP:N-N(of)-------+     |                     
      |           +--MOD_ATT:N-N-+     +--COMP:V-N(in)--+    
      |           |      +MOD_ATT+     |           +MOD_+    
      |           |      |       |     |           |    |    
 Expression of OS 4 [__NODE__] mRNA occurs in NGP 127 cells .
COMP:N-N(of) (expression,mRNA)
MOD_ATT:N-N (mRNA,4)
MOD_ATT:N-N (mRNA,[__NODE__])
SUBJ:V-N (occur,expression)
COMP:V-N(in) (occur,cell)
MOD_ATT:N-N (cell,@card@)