To determine whether Pax6 upregulation in the 7D retina has an effect in retinoblastoma tumorigenesis, we generated Chx10-Cre;RbLox/Lox; −107−/−;;Pax6Lox/Lox (Pax6 TKO) mice and aged them for 400 days. Here, LOX is linked to retinoblastoma.