Inactivation of Rb1 and Trp53 are frequently found mutations in small-cell lung cancer and concomitant loss of Rb1 and Tp53 in mouse lungs leads to a high incidence of SCLC in these mice, recapitulating the aggressive phenotype observed in humans including the formation of extracranial and brain metastasis.20 Here, RB1 is linked to small cell lung carcinoma.