More recently, a cytosolic enzyme, aldehyde dehydrogenase family 1, member A1 (ALDH1), has emerged as a functional, intracellular CSCs marker that is associated with malignancy and self-renewal properties of stem cells in many tumors, including breast [5,6], head and neck [7], melanoma [8], hepatic [9], pancreatic [10], colon [11], lung [12], prostrate [13], bladder [14], ovarian [15], endometrial [16], and cervical [17,18] cancers. Here, ALDH1A1 is linked to cancer.