2096
A GTP / GDP exchange assay was used to assess the potential role of Ras in the pathway leading to ERK phosphorylation ; DADLE failed to stimulate GTP / GDP exchange in comparison to PMA .
 GENE: Ras; GENE: ERK
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: GENE 
Text: {0} 
Answer:
 GENE: Ras; GENE: ERK