To assess whether the profound sensitivity to CHK1 inhibition that we had observed in murine cancer cell lines, was preserved in human SCLC cells, we next performed cell viability measurements in a panel of four human SCLC cell lines (H-526, H-82, N-417, H-69) and three human NSCLC lines (H-1975, HCC-44, A549). The gene discussed is CHEK1; the disease is small cell lung carcinoma.