Gene-expression analysis with quantitative real-time PCR (qPCR) showed that these MTA-resistant cells, irrespective of the NSCLC subtype from which their parental cells were derived, unanimously featured a stem cell-like gene signature characterized by elevated mRNA levels of embryonic stem cell factors Sox2, Oct4 and Nanog (Figure 1a–c), although to a varying extent. This evidence concerns the gene POU5F1 and non-small cell lung carcinoma.