26998
The experimental results suggest that low dose exposure to Cr ( 1 . 0 mu g / cm ( 2 ) ) serves to induce up - regulation of oxidative stress response genes , DNA repair genes and cell cycle regulator genes .
 Cr
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 Cr