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: Unknown
The first gene to be knocked out in the carcinogenesis of endometrium is 
Select and explain. 
A. PI3KCA, B. PTEN, C. KRAS, D. p53
B: PTEN
Answer: B: PTEN 
Explanation: The primary gene involved in transformation of a normal or a hyperplastic endometrium to a neoplastic endometrium is loss of PTEN gene function.