This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
[{'content': 'Which of the following oncogenes is a growth factor? \nSelect and explain. \nA. fos, B. myc, C. jun, D. sis', 'role': 'user'}, {'content': "Answer: D \nExplanation: The 'sis' oncogene is a growth factor. The protooncogene 'sis' encodes the ( b chain of) Platelet Derived Growth Factor (PDGF). Ref: Robbin's Illustrated Pathology, 7th Edition, Pages 293, 295; Cancer: Principles and Practice of Oncology, 6th Edition, Page 13", 'role': 'assistant'}]