4678
Both PPC - 1 and ALVA - 31 cells display tumorigenesis and invasiveness in nude mice , whereas LNCap cells exhibit a less malignant phenotype , suggesting a correlation between CD44 variant ( CD44v ) expression and aggressive prostate tumor behavior .
 CD44 variant, CD44v
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: GENE 
Text: {0} 
Answer:
 CD44 variant, CD44v