27991
To confirm the role of each transporter , we analyzed HEK293 cells stably expressing human ABCA1 or ABCG1 ; we clearly observed 24 - OHC efflux in the presence of HDL , whereas efflux in the presence of apolipoprotein A - I was marginal .
 24 - OHC
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 24 - OHC