More recently, ALDH1A3 inhibitors with a substituted benzaldehyde scaffold have been developed by chemical modification of 4-(diethylamino)benzaldehyde (DEAB, Figure 4) (micromolar IC50 on the recombinant enzyme, Table 3), a known ALDH substrate employed in the AldefluorTM assay, with some compounds showing antiproliferative activity in vitro against prostate cancer tumor cells when added to the culture medium in the micromolar range. This evidence concerns the gene ALDH1A3 and neoplasm.