A study was carried out to examine the effects of CHK1 and PARP inhibitors in vitro using human and murine SCLC cell lines and in vivo using murine RPP/mTmG cells derived from a genetically engineered (GE) SCLC mouse model with the conditional loss of TP53, p130, and Rb (RPP). The gene discussed is TP53; the disease is small cell lung carcinoma.