TP53 and neoplasm: Secondly, our model generated with the second gRNA pair (rb1cr2 and rbl1cr2), with median time of 69 days until retinoblastoma development, shows faster tumor emergence kinetics than the established Chx10-Cre; Rb1Lox/Lox; Rbl1−/−; p53−/− model (Median time until RB development: 100 ± 42.3 days)13.