In this context, aldehyde dehydrogenases class I (ALDH1) has been found to be overexpressed in CSCs and correlated with treatment resistance, within breast cancer [81,82,83], prostate cancer [84,85,86], colorectal cancer [87,88], lung cancer [89,90], ovarian cancer [91,92,93], and many others [94]. Here, ALDH1A1 is linked to breast cancer.