Using the AldefluorTM reagent, which undergoes a shift in fluorescence following enzymatic cleavage by ALDH enzymes, and the ALDH1-specific inhibitor diethylaminobenzaldehyde (DEAB) [34], a large subpopulation of ESA+CD44+ cells from both UM-C4 and UM-C6 tumor lines was determined to have high ALDH activity (Figure 3A) [30]. This evidence concerns the gene ALDH1A1 and neoplasm.