RB1 and neoplasm: Along with CDKN2A gene, which encodes p14ARF and p16INK4A via usage of separate first exons, and signals through p53 and pRb pathway, respectively3, these three CDK inhibitors arranged in tandem on 9p21.3 constitute a prominent tumor suppressor hub that is frequently deleted or epigenetically silenced prior to immortalization of primary cultured cells4–6 and in pre-tumor lesions7,8 and a multitude of tumor types3,4,9–11.