+-----------SUBJ:V-N-----------+                   
      +----COMP:N-N(of)----+         +-COMP:V-N(in)-+    
      |           +MOD_ATT:+         |        +MOD_A+    
      |           |        |         |        |     |    
 Expression of __SP__ __NODE__(s) occurs in HepG2 cells .
COMP:N-N(of) (expression,__NODE__(s))
MOD_ATT:N-ADJ (__NODE__(s),__SP__)
SUBJ:V-N (occur,expression)
COMP:V-N(in) (occur,cell)
MOD_ATT:N-N (cell,HepG2)