The impairment of SCLC cell viability upon treatment with SR9009 was partially due to the induction of apoptosis, as evaluated by immunofluorescence assays for cleaved caspase 3 and terminal deoxynucleotidyl transferase (TdT) dUTP nick end labeling (TUNEL) assays (Figure 2K-N). This evidence concerns the gene DNTT and small cell lung carcinoma.