Bioluminescence tracking of the transplanted mice showed that ectopic expression of YB-1 alone was insufficient to confer tumour-forming capacity on primary human mammary cells and, the addition of KRASG12D expression in the same cells, did not enhance the growth of the tumours generated from cells transduced with KRASG12D alone (Fig. 5A). This evidence concerns the gene YBX1 and neoplasm.