20749
Here , we report that a specific 29 - amino acid peptide derived from the intracellular domain fragment of p75 ( NTR ) interacts with and potentiates binding of NGF to TrkA - expressing cells , leading to increased neurite outgrowth in sympathetic neurons as a result of enhanced Erk1 / 2 and Akt signaling .
 amino acid
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 amino acid