RB1 and cancer: Genes found in transcriptionally repressed regions within cancer cell nuclei include those encoding proteins involved in the regulation of cell cycle progression, DNA repair, apoptosis, and drug metabolism—such as the cyclin-dependent kinase (CDK) 4/6 inhibitor p16/INK4A (encoded by CDKN2A), von Hippel Lindau tumor suppressor gene (VHL), retinoblastoma 1 (RB1), and MutL protein homologue 1 (MHL1) [1, 2].