The phenotype-switching model of tumour progression dictates that these two mutually exclusive populations are able to selectively switch back and forth to drive tumour growth through a predominately proliferative cellular phenotype driven by MITF, and tumour metastasis by an invasive BRN2 directed cellular population (Hoek et al., 2008, Hoek and Goding, 2010). This evidence concerns the gene MITF and neoplasm.