16210
We investigated proteins involved either in the signaling pathways [ RA receptor beta ( RAR beta ) and glucocorticoid receptor ( GR ) ] or in neuron differentiation and plasticity [ tissue transglutaminase 2 ( tTG ) and brain - derived neurotrophic factor ( BDNF ) ] in a hippocampal cell line , HT22 .
 None
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
 Entities:  
Answer:
 None