26753
Platelet - induced COX - 2 - dependent PGE2 synthesis in HT29 cells was involved in downregulation of p21 ( WAF1 / CIP1 ) and upregulation of cyclinB1 , since these effects were prevented by rofecoxib ( a selective COX - 2 inhibitor ) and rescued by exogenous PGE2 .
 Chemical: PGE2; Chemical: rofecoxib; Chemical: PGE2
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: PGE2; Chemical: rofecoxib; Chemical: PGE2