Importantly, the presence of embryonic stem cell and fMaSC signatures in BLBC correlates with poor prognosis 52, 90 and p53 inactivation.26 Recent refinement of the fMaSC signature into sub-signatures reveals that some sub-signature features (e.g., relatedness to basal cancers) predict better chemotherapy response, whereas others predict worse chemotherapy outcomes (e.g., relatedness to luminal tumors).65 This is consistent with the multipotentiality of this primitive cell population. The gene discussed is TP53; the disease is cancer.