Studies of breast cancer stem cells (BCSCs) identified in aggressive breast tumors, such as triple-negative breast cancers (TNBCs), were found to exhibit high aldehyde dehydrogenase (ALDH) activity, which is associated with poor prognosis among breast cancer patients [102,130,131] and is considered to be a CSC marker for other types of cancers [132,133,134]. Here, LDHA is linked to cancer.