+------COMP:V-N(in)------+    
      +--------------SUBJ:V-N-------------+          +MOD_ATT:N-ADJ+    
      +----COMP:N-N(of)---+               |          |     +MOD_ATT+    
      |           +MOD_ATT+          +-NEG+          |     |   +MOD+    
      |           |       |          |    |          |     |   |   |    
 Expression of __SP__ __NODE__ does not occur in immature 3T3 L1 cells .
COMP:N-N(of) (expression,__NODE__)
MOD_ATT:N-ADJ (__NODE__,__SP__)
SUBJ:V-N (occur,expression)
NEG (occur,not)
COMP:V-N(in) (occur,cell)
MOD_ATT:N-ADJ (cell,immature)
MOD_ATT:N-ADJ (cell,3T3)
MOD_ATT:N-N (cell,L1)