PML and neoplasm: Ectopic SOX9-expressing BCa cells were refractory to PML genetic inhibition in terms of the OS formation (Fig. 6d,e) and tumour formation (tumour-initiating cell frequency was estimated of 1/139.8 in shC/Mock, 1/57.5 in shC/SOX9, 1/1506 in sh4/Mock and 1/270.8 in sh4/SOX9; Fig. 6f; Supplementary Fig. 6d).