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