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The results further demonstrated the activation of S6 kinase ( pp90rsk ), evidenced by phosphorylation of S6 and serum response factor (SRF) peptides , in PWM treated B cells .
 PWM, PWM treated B cells, S6 kinase, S6, pp90rsk
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: cell line, protein, RNA, DNA, cell type 
Text: {0} 
Answer:
 PWM, PWM treated B cells, S6 kinase, S6, pp90rsk