Figure 9: Metastasis of CSCs from an invasive tumour. (a) An invasive tumour cell mass results in metastasis of CSCs. (b) A CSC at a secondary site may exhibit restoration of E-cadherin expression leading to establishment within the epithelium. (c) The CSC may divide asymmetrically and symmetrically resulting in TACs and CSCs, however, where the ratio of antiproliferative/proapoptotic (green triangle) to proproliferative/antiapoptotic (red triangle) signals/receptors is high, then a stable neoplasm will form. (d) Alternatively, the pioneer CSC may maintain aberrant E-cadherin expression resulting in a low ratio of antiproliferative/proapoptotic to proproliferative/antiapoptotic signals/receptors and formation of an unstable neoplasm with potential for establishment of a tumour cell mass.