SOX9 and neoplasm: In order to analyse the tumorigenic mechanism of corticomedullary mixed tumour with distinct arrangement of the cortical and medullary layers, we stained the resected tissue for various tumour stem cell-specific markers, including ALDH1, CD44, CD133, Nestin, NGFR, and SOX9, and found short spindle-positive cells scattered within the tumour (Fig. 1c-h), suggesting the involvement of tumour stem cells.