5915
Cadmium ( Cd ) , an inducer of reactive oxygen species , inhibited HIF - 1 alpha mRNA expression and HIF - 1 alpha binding to the LO gene in Co - treated cells as revealed by RT - PCR and ChIP assays , respectively .
 Cadmium, Cd, oxygen, Co
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 Cadmium, Cd, oxygen, Co