CD44 and cancer: Expression levels of known cancer stem cell markers declined under ALK4L75A-Fc treatment, including the majority of aldehyde dehydrogenase (ALDH) transcripts that have been shown to contribute to positivity for the cancer stem cell-associated Aldefluor reagent and the CSC-associated isoforms of CD44 (CD44v3, CD44v6) [41, 42].