Using immunofluorescence, we observed increased steady-state levels of γH2AX (p < 0.0001, one-way analysis of variance (ANOVA)) and DNA double-strand break (DSB) marker 53BP1 (p < 0.0001, one-way ANOVA) in Myc-activated murine SCLC cells suggesting DSB-mediated activation of the DDR in these cells (Fig. 4c, d). Here, MYC is linked to small cell lung carcinoma.