TGFB1 and acute myeloid leukemia: To delineate the specific signaling pathway involved in TGF-β1-induced ALDH activity in AML cells, we treated OCI-AML3 cells with or without cell culture supernatants from BM-MSCs for 0, 30, 60, and 120 minutes and measured phosphorylation of transcription factors that mediate TGF-β1 canonical and non-canonical pathways by Western blotting.