+----------SUBJ:V-N---------+                     
      +----COMP:N-N(of)---+       +--COMP:V-N(in)--+    
      |           +MOD_ATT+       |         +MOD_AT+    
      |           |       |       |         |      |    
 Expression of __SP__ __NODE__ occurs in __SP__ muscle .
COMP:N-N(of) (expression,__NODE__)
MOD_ATT:N-ADJ (__NODE__,__SP__)
SUBJ:V-N (occur,expression)
COMP:V-N(in) (occur,muscle)
MOD_ATT:N-ADJ (muscle,__SP__)