BCSC are characterized by high levels of Aldehyde dehydrogenase (ALDH) activity and increased expression of ALDH isoforms.4 In particular, expression of the ALDH isoform ALDH1A3 is inversely correlated with estrogen receptor signaling5,6 and may be predictive of metastatic potential in invasive breast cancers.7 Here, LDHA is linked to invasive breast carcinoma.