Given the high frequency of genetic anomalies in the CRC and NSCLC setting that render these cancer cells potentially susceptible to CHK1 inhibition, the purpose of the present study was to investigate the in vitro effects of the novel CHK1 inhibitor SRA737 as a single agent on pairs of NSCLC and CRC cell lines of different genetic backgrounds (notably of different TP53 status); specifically, on the level of DNA damage induced and the subsequent effect on cell proliferation/viability. The gene discussed is CHEK1; the disease is cancer.