2680
Indeed , A - MuLV pseudotyped with some viruses , such as the Moloney MuLV , has been shown to be highly lymphogenic , whereas A - MuLV pseudotyped with other viruses , such as the BALB / c endogenous N - tropic MuLV , has been shown to be devoid of lymphogenic potential ( N .
 None
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: GENE 
Text: {0} 
Answer:
 None