ALDH2 and acute myeloid leukemia: Moreover, exposure of AML cells to recombinant TGF-β1 induced ALDH activity through ALDH2 expression, and knockdown of TGF-β1 in BM-MSCs led to a decrease in ALDH activity, indicating that TGF-β1 secreted by BM-MSCs induces a stem-like phenotype in AML cells.