Aldehyde dehydrogenase (ALDH) activity, used as a marker for prostate cancer stem cells (Moreb, 2008; Burger et al, 2009; Li et al, 2010; Yu et al, 2011), has an important role in maintaining antioxidative capacity and CD44, known to characterise cancer stem cells and to correlate with the ability of prostate cancer cells to migrate, regulates redox status in cancer cells (Klarmann et al, 2009; Ishimoto et al, 2011). Here, CD44 is linked to cancer.