28582
Platelet - derived growth factor - BB ( PDGF ) - induced proliferation of human coronary artery VSMCs was attenuated by lowering intracellular Ca ( 2 + ) concentration ( [ Ca ( 2 + ) ] i ) and was enhanced by elevating [ Ca ( 2 + ) ] i .
 Ca ( 2 + ), Ca ( 2 + ), Ca ( 2 + )
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 Ca ( 2 + ), Ca ( 2 + ), Ca ( 2 + )