PARP1 and small cell lung carcinoma: Unsupervised cluster analysis of Illumina HT-12 data comparing the baseline gene expression profile of untreated SCLC cell lines showed tight clustering of 5 cell lines (H146, H187, H209, H526, and DMS114), which were mostly the same cell lines that displayed increased sensitivity to cisplatin and to PARP inhibition (arbitrarily defined as at least 50% reduction in the IC50 concentration of cisplatin when combined with veliparib; Fig. 6A).