321
A tetracycline - inducible transgenic mouse model expressing truncated beta - catenin ( Delta N89 beta - catenin ) that exhibited a strong intestinal hyperplasia was analyzed during the removal of oncogenic beta - catenin expression both in 3D ' crypt culture ' and in vivo .
 tetracycline
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 tetracycline