This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General pathology, Subject name: Pathology
Following is called "gatekeeper of colonic neoplasia" 
Select and explain. 
A. APC, B. SMAD2, C. PTEN, D. STK11
A: APC
Answer: A: APC 
Explanation: Adenomatous polyposis coli (APC) gene Chr 5q21 Gate-keeper of colonic neoplasia Component of WNT signalling pathway Controls cell fate, polarity and adhesion during embryonic devt Controls oncogenic effect of b catenin Germline LOF mutation - Familial Adenomatous Polyposis Colon Cancer (AD) Other tumours - hepatoblastoma, HCC