THY1 and acute lymphoblastic leukemia: The BM‐MSCs were immunophenotyped via flow cytometry analysis of surface antigen expression, specifically MSC defining markers (CD45‐CD34‐CD73 + CD90 + CD105+); there were no significant differences in the expression of MSC defining markers between ND‐MSCs and B‐ALL‐MSCs (Figure S2A,B).