23533
Of 9 CGPs with IC50 ' s <= 2 mu M , two belonged to Class I , two to Class III and five to Class V . When tested in the intact cells , only 4 of 16 CGPs ( at 10 mu M ) inhibited MRP1 - mediated calcein efflux by > 50 % ( III - 1 , V - 3 , - 4 , - 6 ) while a fifth ( I - 5 ) inhibited efflux by just 23 % .
 CGPs, CGPs, calcein
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 CGPs, CGPs, calcein