A representative western blot (Figure 3A) shows that AML exosomes carry the TGF-β1 pro-peptide consisting of the LAP covalently bound to mature TGF-β1 (~50 kDa), cleaved LAP (~37 kDa) and mature TGF-β1 (~25 kDa), which under reducing conditions may dissociate into 2 × 12.5 kDa chains (12, 13). Here, TGFB1 is linked to acute myeloid leukemia.