The Rb1 and Trp53 (RP) model involves using immunocompetent mice with conditional mutant alleles for Rb1 and Trp53 that are flanked by lox sites (Rb1flox/flox;Trp53flox/flox mice) that receive intratracheal administration of an adenoviral vector expressing Cre recombinase under the control of a CMV promoter (Ad-CMV-Cre), resulting in loss of function of Rb1 and Trp53 in the lungs for SCLC initiation [86]. Here, TP53 is linked to small cell lung carcinoma.