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
Event of early acquisition of malignant phenotype of epithelium is an expression of: 
Select and explain. 
A. Cyclin a, B. Cyclin b, C. Cyclin c, D. Cyclin d
D: Cyclin d
Answer: D: Cyclin d 
Explanation: Conclusion of this study was Deregulation of the p16/ pRb/cyclin DI pathway is an early event in acquisition of dysplasia, but deregulation of both pRb and p53 pathway is associated with malignant transformation and adverse prognosis in oral tumorigenesis.