HRAS and breast cancer: This transformation model system was originally developed by Weinberg and his colleagues in 1999, which has been accomplished oncogenic transformation through the viral-mediated serial gene transfer of three defined elements, SV40, hTERT and hRAS-V12, to normal human epithelial cells [25], [26] Although these individual genetic mutations are not universally found in all types of breast cancer, the model has been widely used for breast cancer research since it can closely approximate the initiation and early progression of breast cancer [27], [42].