+----------------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__ PGC 1 [__NODE__] mRNA occurs in C2C12 cells .
COMP:N-N(of) (expression,mRNA)
MOD_ATT:N-ADJ (mRNA,__SP__)
MOD_ATT:N-N (mRNA,1)
MOD_ATT:N-N (mRNA,[__NODE__])
SUBJ:V-N (occur,expression)
COMP:V-N(in) (occur,cell)
MOD_ATT:N-N (cell,C2C12)