19581
Regucalcin ( RGN / SMP30 ) was originally discovered in 1978 as a unique calcium - binding protein that does not contain the EF - hand motif of calcium - binding domain .
 calcium, calcium
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 calcium, calcium