In particular, the in vitro results showed the ability of A549 cisplatin-resistant cells to form spheres is greater than that of A549 cells, modulating the expression levels of tumour stem cell biomarkers, such as β-catenin, Nanog, octamer-binding transcription factor 3,4 (October 3, 4), SRY-box transcription factor 2 (Sox2), c-Myc and KLF transcription factor 4 (Klf4) (Liu et al., 2016). This evidence concerns the gene SOX2 and neoplasm.