2239
The effects of IGF - 1 are mediated principally through the IGF - 1R but are modulated by complex interactions with multiple IGF binding proteins that themselves are regulated by phosphorylation , proteolysis , polymerization , and cell or matrix association .
 cell, matrix
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Anatomy 
Text: {0} 
Answer:
 cell, matrix