The mouse MYCN-induced Rb1−/− cells were not described as expressing photoreceptor genes [26] in accordance with several mouse retinoblastoma models, including the Rb1−/−Rbl2−/− mice that do not express specific cPR profiles but rather profiles with ACs and HCs, suggesting an alternative cell of origin [55, 56]. The gene discussed is POR; the disease is retinoblastoma.