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To elucidate the molecular mechanism by which the Ras signaling pathway activates a cell - type - specific gene , we have used the pituitary - specific rat prolactin ( rPRL ) promoter as a target of oncogenic Ras and Raf in GH4 rat pituitary cells .
 GENE: Ras; GENE: pituitary - specific rat prolactin; GENE: rPRL; GENE: oncogenic Ras; GENE: Raf
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: pituitary - specific rat prolactin; GENE: rPRL; GENE: oncogenic Ras; GENE: Raf