Fig 1: Upregulation of YBX1 protein cargo inside AML‐derived sEVs. (a) Western blot analysis of YBX1 in various AML and non‐AML samples. C1‐C15 and P1‐P15 indicates sEVs isolated from peripheral blood plasma of 15 paediatric healthy controls and 15 paediatric AML patients, respectively. (b) Quantification of YBX1 expression using ELISA (N = 15 for paediatric healthy control and AML patient sEVs). (c) Table showing the level of YBX1 (ng/mL) on various paediatric AML patients sEVs. Evaluation of YBX1 expression on BM‐MSCs treated with AML and non‐AML sEVs. sEVs were incubated with BM‐MSCs in the ratio of 50:1 (50 sEV particles per cell). (d) Immunoblotting of GAPDH and YBX1 on untreated BM‐MSCs and BM‐MSCs treated with different sEVs. Quantification of YBX1 relative to corresponding GAPDH signal. (e) Relative YBX1‐mRNA level on untreated BM‐MSCs and BM‐MSCs treated with different sEVs using qRT‐PCR. (f) Demonstration of the location of YBX1 cargo in leukaemia sEVs by incubation with Proteinase K (Prot K) and Triton X. Electroporation‐based downregulation of YBX1 in MV4‐11 cells. (g) Determination of YBX1 relative mRNA and protein level on MV4‐11 cells transfected with si‐YBX1 using qRT‐PCR, ELISA and western blot. Data illustrated in b, e, f and g for the cell line and their corresponding sEVs are mean ± S.E.M. of n = 3 experiments. All p values were calculated using one‐way ANOVA with Dunnett's multiple comparisons test except the ELISA analysis in f in which p‐value was calculated using an unpaired t‐test (****p < 0.0001, ***p < 0.001, **p < 0.01, *p < 0.05 and ns‐ non‐significant).