Additional instances include the expression of SOX2/SOX9 in DTCs, which leads to the initiation of metastasis following a latency period in breast cancer, as well as the promotion of metastasis by SLUG/SOX9 and the stemness regulator miR-199a in both normal and cancer cells, favouring the initiation of tumours and metastases [53,54,55]. Here, SOX9 is linked to breast cancer.