ALDH1A1 and prostate cancer: Recent studies have revealed that aldehyde dehydrogenase1A1 (ALDH1A1), an aldehyde oxidase that can degrade toxic aldehydes in cells to maintain a stable environment in the cell, was a marker for malignant prostate stem cells and predictor of prostate cancer patients’ outcome (Yoshida et al., 1992; Li et al., 2010).