Specifically, in this report we showed that the MTS assay is not on its own trustworthy as a method to measure the anti-proliferative activity of ICI 182780 which is clinically used for the treatment of advanced breast cancer [20], nor is it a reliable method to assess the anti-proliferative capacity of p14ARF-p53, an important tumor suppressor pathway. This evidence concerns the gene TP53 and breast cancer.