1916
Since these findings supported the involvement of serine /threonine protein phosphorylation in the regulation of EGR-1 expression , we studied activation of the 40S ribosomal protein S6 serine /threonine kinases , pp70S6K and pp90rsk .
 pp70S6K, pp90rsk, 40S ribosomal protein S6 serine /threonine kinases, EGR-1
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:
 pp70S6K, pp90rsk, 40S ribosomal protein S6 serine /threonine kinases, EGR-1