CDKN2A and neoplasm: Cyclin-dependent kinase inhibitor 2A (CDKN2A) alteration is the most common focal deletion in UC and is found in up to 20–30% of tumours.3,4 Loss of CDKN2A leads to upregulation of cyclin-dependent kinase (CDK) 4 and 6 activity, thus phosphorylating and inactivating the tumour suppressor Rb, leading to cell cycle progression and tumour growth.