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
Colon carcinogenesis is associated with all of the following genetic mutations, EXCEPT: 
Select and explain. 
A. APC, B. kRAS, C. B- catenin, D. HER2 gene
D: HER2 gene
Answer: D: HER2 gene 
Explanation: Amplification of the HER2 gene and overexpression of the HER2 protein are common in preinvasive and invasive breast cancers. The earliest molecular defect in the pathogenesis of colon cancer is the acquisition of somatic mutations in the APC gene in the normal colonic mucosa. This defect causes abnormal regulation of -catenin, which leads to abnormal cell proliferation and the initial steps in tumor formation. Mutational activation of the K-ras gene leads to constitutive activation of an impoant proliferative signaling pathway, is common at these stages, and fuher increases the proliferative potential of the adenomatous tumor cells. Ref: Moasser M.M. (2010). Chapter 5. Neoplasia. In S.J. McPhee, G.D. Hammer (Eds), Pathophysiology of Disease, 6e.