22808
Compounds 16 and 19 were more active than the positive control PD98059 , a known inhibitor of the ERK1 / 2 signaling pathway .
 Chemical: PD98059
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: PD98059