Regulation of cancer stem cell properties by CD9 in human B-acute lymphoblastic leukemia

► We performed more detailed analysis of CD9 function for CSC properties in B-ALL. ► Leukemogenic fusion/Src family proteins were markedly regulated in the CD9+ cells. ► Proliferation of B-ALL cells was inhibited by anti-CD9 monoclonal antibody. ► Knockdown of CD9 by RNAi remarkably reduced the leukemogenic potential. ► CD9-knockdown affected the expression and phosphorylation of Src family and USP22.