One hit, two hits, three hits, more? Genomic changes in the development of retinoblastoma

The childhood eye cancer retinoblastoma is initiated by the loss of both alleles of the prototypic tumor suppressor gene, RB1 . However, a large number of cytogenetic and comparative genomic hybridization (CGH) studies have shown that these M1 and M2 mutational events—although necessary for initi…